TR41 1 05 05 008 TIA 1062 VoIP T1 Gateway Standard D4 by HC12083104287

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                                                                               TR41.1/054-0508-00811A

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                                                                  Make separate contribution #00x??

STANDARDS PROJECT:              Standard for 1544 kbps VoIP gateways


TITLE:                          1544 kbps network interface requirements for packet-basedVoIP
                                gateways - Draft 41


ISSUES ADDRESSED:               New standard for 1544 kbps packet-basedVoIP gateways


SOURCE:                         Siemens ICommunications, Inc.N

                                                                                                              Formatted: French (France)
CONTACT:                        Tailey Tung
                                Phone: 408-492-5049
                                Fax: 408-492-2563
                                Email: tailey.tung@icn.siemens.com                                            Formatted: Hyperlink, French (France)
 Kirit comments                                                                                              Field Code Changed
                                                                                                              Formatted: French (France)
                                                                                                              Formatted: French (France)
DATE:                           MayAugust 122, 20054.


DISTRIBUTION TO:                TIA TR41.1


KEYWORDS:                       ANSI/TIA-1062 - 1544 kbps packet-basedVoIP gateway




NOTICE: The contributor grants a free, irrevocable license to the Telecommunications Industry
Association (TIA) to incorporate text or other copyrightable material contained in this contribution and
any modifications thereof in the creation of a TIA Publication; to copyright and sell in TIA's name any
TIA Publication even though it may include all or portions of this contribution; and at TIA's sole
discretion to permit others to reproduce in whole or in part such contribution or the resulting TIA
Publication. This contributor will also be willing to grant licenses under such copyrights to third parties
on reasonable, non-discriminatory terms and conditions for purpose of practicing a TIA Publication which
incorporates this contribution.

This document has been prepared by Siemens ICN to assist the TIA Engineering Committee. It is
proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on
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Siemens ICN. Siemens ICN specifically reserves the right to amend or modify the material contained
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herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to
any intellectual property of Siemens ICN other than provided in the copyright statement above.                Formatted: Not Highlight
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Changes in Draft 2 – 11/2004.                                                                                 Numbered + Level: 1 + Numbering Style: 1, 2,
                                                                                                              3, … + Start at: 1 + Alignment: Left + Aligned
1. Changed VoIP gateway to packet-based gateway.                                                              at: 0" + Tab after: 0.25" + Indent at: 0.25"
2. Modified Introduction and Scope.                                                                           Formatted: Bullets and Numbering

3. Added connection diagram to Scope section.                                                                 Formatted: Normal Indent, Space After: 6 pt,
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4. Defined T1 and Voice Gateway based on TIA-912A,section 4.1.                                                Formatted: Font: Bold, Italic, Underline
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Changes in Draft 3 – 2/2005.
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1.   The figure in the scope section shows the VoIP T1 gateway can also support interface to enterprise       Numbered + Level: 1 + Numbering Style: 1, 2,
                                                                                                              3, … + Start at: 1 + Alignment: Left + Aligned
     network.                                                                                                 at: 0" + Tab after: 0.25" + Indent at: 0.25",
                                                                                                              Tab stops: 0.33", List tab
2.   Section 5.2.2.2 powering requirements should include information concerning the voltage that should
     be specified.                                                                                            Formatted: Bullets and Numbering
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3.   Add Channel Associated Signaling (CAS) requirements.                                                     Roman, Not Bold
4.   Add QSIG requirements.                                                                                   Formatted                                    ...
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Changes in Draft 4 – 5/2005.                                                                                  Formatted                                    ...

1. Re-drawn the figure in the scope section to show the connection of T1 gateway to PSTN and the              Formatted                                    ...
   enterprise network.                                                                                        Formatted                                    ...
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2. Removed AMI (Alternate Mark Inversion) with ZCS (Zero Code Suppression) from Section 5.1.
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3. Deleted all references to AMI from tables.
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4. Removed all AMI related requirements from the draft.                                                       Formatted                                    ...
5. Revised Table for DSX-1.                                                                                   Formatted                                    ...

6. Reviewed Tables for DS-1 and DSX-1 to make them consistent with the line rate values.                      Formatted                                    ...
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7. Section 5.2.2.2 power requirement voltage value of -130Vdc needs to be reviewed because some CSU
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   have much higher voltages. Trone Bishop of Verizon will verify this value.
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8. Removed section 5.2.4.1 pulse density requirements with the deletion of AMI.
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9. Removed SF (SuperFrame) from section 5.3 leaving ESF (Extended SuperFrame) the only required               Formatted: Not Highlight
   signaling format.
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10. Removed all SF related requirements.                                                                      Formatted                                    ...
11. Accepted Cisco proposal to add echo cancellation requirements to section 6.2.                             Formatted                                    ...

12. Accepted 8ms to 128 ms instead of 24ms to 128 ms echo tail requirement for echo cancellation.             Formatted                                    ...
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13. Changed “TSB116” to “TSB116-A”.
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14. Added a statement in section 8.3.2 to recognize that some gateways will not comply with other call        Formatted                                    ...
    progress signals.
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15. Section 5.3.4 references T1.231. Kirit Patel of Cisco will verify the requirements in section 5.3.4 are   Formatted                                    ...
    same as those in T1.231.
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                                                First Draft - 4
                                             SP-3-10903xxx
                           (to be published as ANSI/TIA-1062xxx)



                                         Telecommunications


                   Telephony Aspects of MLTS and VoIP Equipment

                                                                                                                   Formatted: Highlight
 1544 kbps Network Interface Requirements for Packet-basedVoIP Gateways



                     Formulated under the cognizance of TIA Subcommittee TR-41.1,
                             Telephony Aspects of MLTS and VoIP Equipment


                         With the approval of TIA Engineering Committee TR-41,
                             User Premises Telecommunications Requirements




                                    _____________________________


                                                  NOTICE
This is a draft document. It may be changed or modified. Neither TIA nor TR41.1 Sub-Committee
makes any representation or warranty, express or implied, with respect to the sufficiency, accuracy or
utility of the information or opinion contained or reflected in the material utilized. TIA and TR41.1 Sub-
Committee further expressly advise that any use of or reliance upon the material in question is at your risk
and neither TIA nor TR41.1 Sub-Committee shall be liable for any damage or injury, of whatever nature,
incurred by any person arising out of any utilization of the material. It is possible that this material will at
some future date be included in a copyrighted work by TIA.
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                                               TABLE OF CONTENTS
         FOREWORD .................................................................................................................... 1
1        INTRODUCTION ............................................................................................................. 2
1.1      Purpose .............................................................................................................................. 2
1.2      Categories of Performance Criteria ................................................................................... 2
2        SCOPE .............................................................................................................................. 3
2.1      Compliance Reference Point ............................................................................................. 3
2.2      Compliance Interpretation ................................................................................................. 3
2.3      Conformance with Regulatory and Safety Standards ........................................................ 3
3        NORMATIVE and INFORMATIVE REFERENCES ...................................................... 4
4        DEFINITIONS, ABBREVIATIONS and ACRONYMS.................................................. 5
4.1      Definitions ......................................................................................................................... 5
4.2      Abbreviations and Acronyms ............................................................................................ 7
5        DS1 and DSX-1 NETWORK INTERFACE REQUIREMENTS ..................................... 8
5.1      Electrical and Physical Characteristics.............................................................................. 8
5.2      Electrical Interfaces ........................................................................................................... 9
5.3      Signal Formats................................................................................................................... 18
5.4      ISDN Primary Rate Access (DSS1) Requirements ........................................................... 37
6        TRANSMISSION REQUIREMENTS.............................................................................. 37
7.       DTMF GENERATOR and RECEIVER CHARACTERISTICS ...................................... 38
7.1      General .............................................................................................................................. 38
7.2      DTMF Generator Characteristics ...................................................................................... 39
7.3      DTMF Receiver Characteristics ........................................................................................ 40
8        CALL PROGRESS SIGNALING..................................................................................... 41
8.1      Call Progress Signals Sent to the PSTN ............................................................................ 41
8.2      Definitions of Standard Call Progress Signals .................................................................. 41
8.3      Electrical Standards for Call Progress Signals .................................................................. 42
Annex A. Bibliography ...................................................................................................................... 43
FOREWORD 31
1        INTRODUCTION ............................................................................................................. 42
1.1      Purpose .............................................................................................................................. 42
1.2      Categories of Performance Criteria ................................................................................... 42
2        SCOPE .............................................................................................................................. 53
2.1      Conformance with Regulatory and Safety Standards ........................................................ 63
3        NORMATIVE and INFORMATIVE REFERENCES ...................................................... 74
4        DEFINITIONS, ABBREVIATIONS and ACRONYMS.................................................. 96
4.1      Definitions ......................................................................................................................... 96
4.2      Abbreviations and Acronyms ............................................................................................ 118
5        DS1 and DSX-1 NETWORK INTERFACE REQUIREMENTS ..................................... 1310
5.1      Electrical and Physical Characteristics.............................................................................. 1310
5.2      Electrical Interfaces ........................................................................................................... 1411
5.3      Signal Formats................................................................................................................... 2520
5.4      ISDN Primary Rate Access (DSS1) Requirements ........................................................... 4437
5.5      ISDN Private Network Signaling (PSS1 / QSIG) Requirements ...................................... 4437
5.6      Channel-associated Signaling and Supervision Requirements .......................................... 4740
6        TRANSMISSION REQUIREMENTS.............................................................................. 5144
6.1      General .............................................................................................................................. 5144
6.2      Echo Cancellation.............................................................................................................. 5144
7        DTMF SIGNALING REQUIREMENTS ......................................................................... 5245
7.1      General .............................................................................................................................. 5245
7.2      DTMF Generator Characteristics ...................................................................................... 5346
7.3      DTMF Receiver Characteristics ........................................................................................ 5447
8        CALL PROGRESS SIGNALING..................................................................................... 5649
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8.1      Call Progress Signals Sent to the VoIP networks .............................................................. 5649
8.2      Definitions of Call Progress Signals.................................................................................. 5952
8.3      Electrical Standards for Call Progress Signals .................................................................. 6154
Annex A. Bibliography ...................................................................................................................... 6755




LIST OF FIGURES
Figure 1 - VoIP Gateway 1544 kbps Network Interface Connections.................................................. 8
Figure 2 - DSX-1 Cross-Connect Isolated Pulse Template .................................................................. 10
Figure 3 - DS1 VoIP Gateway Interface Isolated Pulse Template........................................................ 12
Figure 4 - Pulse Amplitude Envelope with 60 Hz Longitudinal Currents ............................................ 13
Figure 5 - Frequency Weighting Function for Band 1 Jitter Specification ........................................... 16
Figure 6 - Frequency Weighting Function for Band 2 Jitter Specification ........................................... 16
Figure 7 - Example of Bipolar Eight Zero Substitution (B8ZS) ........................................................... 17
Figure 8 - Example of Alternate Mark Inversion with Zero Code Suppression ................................... 18
Figure 9 - 1544 kbps Signal Format...................................................................................................... 19
Figure 10 - Superframe Framing Format ................................................................................................ 20
Figure 11 - Extended Superframe Framing (ESF) F-Bit Assignments ................................................... 22
Figure 12 - ESF/CMB Relationship ........................................................................................................ 23
Figure 13 - Mathematical Check-Bit Generation .................................................................................... 23
Figure 14 - Performance Report Message Structure ............................................................................... 28
Figure 1 - Packet-based Gateway 1544 kbps Interface Connections .................................................... 1310
Figure 2 - DSX-1 Cross-Connect Isolated Pulse Template .................................................................. 1512
Figure 3 - DS1 Packet-based Gateway Interface Isolated Pulse Template ........................................... 1814
Figure 4 - Pulse Amplitude Envelope with 60 Hz Longitudinal Currents ............................................ 1815
Figure 5 - Frequency Weighting Function for Band 1 Jitter Specification ........................................... 2218
Figure 6 - Frequency Weighting Function for Band 2 Jitter Specification ........................................... 2218
Figure 7 - Example of Bipolar Eight Zero Substitution (B8ZS) ........................................................... 2319
Figure 8 - 1544 kbps Signal Format...................................................................................................... 2620
Figure 9 - Extended Superframe Framing (ESF) F-Bit Assignments ................................................... 2922
Figure 10 - ESF/CMB Relationship ........................................................................................................ 3023
Figure 11 - Mathematical Check-Bit Generation .................................................................................... 3023
Figure 12 - Performance Report Message Structure ............................................................................... 3528
Figure 13 - QSIG Protocol Model........................................................................................................... 4538




LIST OF TABLES
Table 1 - Assigned Bit-patterned ESF Data Link Messages ................................................................... 30
Table 2 - Unassigned ESF Data Link Codewords .................................................................................. 31
Table 3 - Example - ESF Data Link Performance Report Messages .................................................... 32
Table 4 - Standard Call Progress Signals ................................................................................................ 42
Table 1 - Assigned Bit-patterned ESF Data Link Messages ................................................................... 3730
Table 2 - Unassigned ESF Data Link Codewords .................................................................................. 3831
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Table 3 - Example - ESF Data Link Performance Report Messages .................................................... 3932
Table 4 - Interface Type and Channel Unit Equivalent .......................................................................... 4740
Table 5 - Standard Call Progress Signals ................................................................................................ 5750
Table 6 - Other Call Progress Signals ..................................................................................................... 5851
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                                          FOREWORD
                              (This foreword is not part of this standard.)


This document is a TIA Telecommunications Standard produced by TIA Engineering Technical
Subcommittee TR-41.1 of Committee TR-41. This standard was developed in accordance with TIA
procedural guidelines, and represents the consensus position of the subcommittee TR-41.1, which served
as the formulating group.


The TR-41.1 Engineering Technical Subcommittee acknowledges the contribution made by the following
individuals in the development of this standard.

                      Name                         Representing                                          Formatted Table




        Kirit Patel                   Cisco Systems



        Tailey Tung                   Siemens Communications, Inc.            Chair & Editor



        Tailey Tung                   Siemens ICN                             Chair & Editor


Copyrighted parts of ANSI, IEEE, ISO standards and ITU-T Recommendations are used with permission
of these organizations. The ANSI, IEEE, ISO and ITU-T own the copyright for their standards.


Suggestions for improvement of this standard are welcome. They should be sent to:
                               Telecommunications Industry Association
                                      Engineering Department
                                             Suite 300
                                       250 Wilson Boulevard
                                       Arlington, VA 22201
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1           INTRODUCTION
This standard is one of a series of technical standards on telephony aspects of user premises VoIP
equipment prepared by TIA Engineering Technical Subcommittee TR-41.1 of Committee TR-41. This
document fills a recognized need in the telecommunications industry, brought about by the connecting of
public and private networks using Voice over Internet Protocol (VoIP) gateways with 1544 kbps network
interfaces supplied by different manufacturers. It will be useful to anyone engaged in the manufacture of
1544 kbps packet-basedVoIP gateway equipment and to those purchasing, operating, or using such              Formatted: Highlight
equipment.
The requirements in this standard are specified at the interface between the packet-basedVoIP gateways
and the public and private networks. They are formulated to ensure compatibility of the 1544 kbps
packet-basedVoIP gateway equipment for communications over the Internet and packet switched
networks with the public and private network 1544 kbps DS1 and DSX-1 equipment.

1.1         Purpose
This standard establishes performance and technical criteria for interfacing and connecting the packet-
based VoIP gateway 1544 kbps network interface with the public and private network 1544 kbps DS1 and
DSX-1 equipment. It is not intended to be an equipment specification. Compliance with this standard
should assure interoperability between equipmentquality service. In some cases, quality performance
requires location-oriented options or equipment changes in the public and private network DS1 and DSX-
1 equipment. This flexibility is needed to accommodate differences between equipment. To assure
satisfactory performance, two items are needed: equipment design compliance and a process for
configuring the packet-based VoIP gateways to the requirements of the 1544 kbps DS1 and DSX-1
equipment.

1.2         Categories of Performance Criteria
In accordance with TIA Engineering Style Manual for Standards and Publications, two categories of
performance standards are specified, mandatory and advisory. The mandatory requirements are
designated by the word "shall". Advisory requirements are designated by the word "should”, "may”, or
"desirable" (which are used interchangeably in this standard). The mandatory criteria generally apply to
safety and protection, signaling and compatibility. They specify the absolute minimum acceptable
performance levels in areas such as signaling and equipment parameters.
Advisory or desirable criteria represent product goals or are included in an effort to assure universal
product compatibility. In other cases, advisory criteria are presented when their attainment will enhance
the general performance of the product in all its contemplated applications.
Where both a mandatory and an advisory level are specified for the same criterion, the advisory level
represents a goal currently identifiable as having distinct compatibility or performance advantages, or
both, toward which future designs should strive.
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2           SCOPE
This standard defines the electrical requirements and telephony aspects (e.g. DTMF and call progress
tones) of the 1544 kbps and physical interface of requirements for packet-basedVoIP gateways for           Formatted: Highlight
connection to public or private switching telephone networks (PSTN) with 1544 kbps network interfaces.
Other interfaces (e.g. LAN interface) for connection to IP or packet-based network are outside the scope   Formatted: Highlight
of this standard. Because of the changing environment in telecommunications and the introduction of        Formatted: Highlight
new technology, this document will be a living document with periodic revisions issued by TIA
                                                                                                           Formatted: Highlight
engineering Sub-committee TR41.1.
In this standard, the VoIP gateway with 1544 kbps network interface is referred to as the VoIP gateway.
It is considered to be a privately owned customer premises equipment that performs switching functions
between VoIP gateway and public network digital trunk interfaces, and between VoIP gateways.




Compliance with this standard is determined at the packet-based gateway 1544 kbps interface boundary
and is not to be construed as a constraint on the internal coding or switching techniques of the packet-
based gateway.


The requirements in this standard ensure compatibility of packet-based VoIP gateway with the 1544 kbps
digital trunk interface parameters specified in ANSI/TIA-464-C, PBX switching equipment (Ref.12) and
ANSI T1.403, DS1 Electrical Interface (Ref 2).
The packet-based gateway with 1544 kbps interface is referred to as the packet-based gateway within this
standard.
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The voicegrade digital transmission requirements are dependent on the compression algorithm utilized to
transport the packetized voice signal. These requirements are derived from the existing circuit switched
environment based on a full 64 kbps voice channel that are relevant only for the G.711 audio codec
specified in ITU-T Recommendation G.711-1993, Pulse Code Modulation of Voice Frequencies (Ref 15).
Other audio codec compression algorithms are not addressed in this standard.
The requirements in this standard are intended to assure satisfactory user voicegrade services in a high
percentage of installations. If cases arise that have not been adequately addressed in this standard, any
resulting problems should be resolved through the cooperation of the customer, the carrier, and the
equipment supplier.

2.1         Compliance Reference Point
Compliance with this standard is determined at the VoIP gateway 1544 kbps network interface boundaries
and is not to be construed as a constraint on the internal coding or switching techniques of the VoIP
gateway.

2.2         Compliance Interpretation
A VoIP gateway complies with this standard when it conforms to the requirements applicable to the
interfaces with which it is equipped. For satisfactory service, a VoIP gateway should be capable, through
the proper selection of equipment options, of satisfying the requirements applicable to its serving area.
The requirements for the individual types of VoIP gateway interfaces vary between public network and,
in some cases, between network switching equipment; therefore, multiple options are stated for satisfying
a particular requirement.

2.13        Conformance with Regulatory and Safety Standards
This standard is intended to be in conformance with Part 68 of the FCC Rules and Regulations (Ref 3),
ANSI/TIA-968-A standard (Ref 6) and with the safety requirements specified in UL 60950-1 Standard for
Safety of Information Technology Equipment (Ref 4), but it is not limited to the scope of these rules or
requirements. If the requirements in either of these documents are more stringent than those contained in
this standard, the provisions of those documents apply. In addition to the requirements in this standard, a
packet-based VoIP gateway is subject to environmental considerations given in ANSI/TIA-571-A-1998,
Telecommunications User Premises Equipment Environmental Considerations (Ref 5).
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3           NORMATIVE and INFORMATIVE REFERENCES
The following standards contain provisions, which, through reference in this text, constitute provisions of
this Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this standard are encouraged to investigate the possibility of
applying the most recent editions of the standards indicated below. ANSI and TIA maintain registers of
currently valid national standards published by them.
[1]     ANSI Standard EIA/TIA-464-C-2002, Requirements for Private Branch Exchange (PBX)
        Switching Equipment and its addendum
[2]     ANSI T1.403-2000 for telecommunications – Network to Customer Installation Interfaces - DS1
        Interface
[3]     Part 68 of the FCC Rules and Regulations
[4]     UL/CSA 60950-01, Standard for Safety of Information Technology Equipment
[5]     ANSI Standard EIA/TIA-571-A-1998, Telecommunications - User Premises Equipment -
        Environmental Considerations
[6]     ANSI/TIA-968-A-2003 for Telecommunications - Telephone Terminal Equipment - Technical
        Requirements for Connection of Terminal Equipment to the Telephone Network and its addenda
[7]     ANSI Standard T1.101-1999 for telecommunications - Synchronization Interface Standard
[8]     ANSI/TIA-594-B-2004, Information technology - Telecommunications and information
        exchange between systems - Synchronization methods and technical requirements for Private
        Integrated Services Networks
[9]     ANSI Standard T1.107-1995 for telecommunications - Digital Hierarchy - Formats Specifications
[10]    ITU-T Recommendation Q.921-1984, ISDN User-Network Interface Data Link Layer
        Specification
[11]    ANSI Standard T1.403.01-1999 for telecommunications - Integrated Services Digital Network
        (ISDN) Primary Rate Layer 1 Electrical Interface Specification (revision and redesignation of
        ANSI T1.408-1990)
[12]    ANSI Standard T1.602-1996 for telecommunications - ISDN - Data-Link Layer Signaling
        Specification for Application at the User-Network Interface
[13]    ANSI Standard T1.607-2000 for telecommunications – Integrated Services Digital Network
        (ISDN) - Layer 3 Signaling Specification for Circuit-Switched Bearer Service for Digital
        Subscriber Signaling System Number 1 (DSS1)
[14]    ANSI Standard T1.231-1997 for telecommunications - Digital Hierarchy - Layer 1 in-service
        digital transmission performance monitoring
[15]    ITU-T Recommendation G.711-1993, Pulse Code Modulation of Voice Frequencies
[16]    T1 Technical Report No. 5 - 1999 for Network and Customer Installation Interface Connector
        Wiring Configuration Catalog
[17]    ATIS T1X1 Technical Report No. 33
[18]    ANSI/TIA-912-A-2003 for Telecommunications - IP Telephony Equipment - Voice Gateway
        Transmission Requirements
[19]    ANSI Standard T1.508-2004, Network Performance - Loss Plan for Evolving Digital Networks
[20]    TIA/TSB/EIA-32-A-1998 for Telecommunications - Overall Transmission Plan Aspects for
        Telephony in a Private Network
[21]    TIA/TSB/EIA-116-A-20051 for Telecommunications - IP Telephony Equipment - Voice Quality               Formatted: Highlight

        Recommendations for IP Telephony
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[22]   ISO/IEC 11579-1:1994, Information technology - Telecommunications and information exchange
       between systems – Private Integrated Services Network – Part 1: Reference configuration for
       PISN Exchanges (PINX)
[23]   ISO/IEC 11582:1995, Information Technology - Telecommunications and information exchange
       between systems - Private Integrated Services Network - Generic functional protocol for the
       support of supplementary services - Inter-exchange signaling procedures and protocol
[24]   ISO/IEC 11572:2000, Information technology - Telecommunications and information exchange
       between systems - Private Integrated Services Network - Circuit Mode Bearer Services - Inter-
       exchange signaling procedures and protocol
[25]   ITU-T Recommendation Q.931 - Digital subscriber signaling system No.1 - Network layer -
       ISDN user-network interface layer 3 specification for basic call control


[26]   TIA/EIA TSB123-2000, Telecommunications - Multiline Terminal Systems - North American
       Test Plan for Multi-Vendor QSIG Interoperability Testing
[27]   ITU-T Recommendation G.168 - Digital network echo cancellers                                     Formatted: French (France)
                                                                                                        Formatted: French (France)
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4           DEFINITIONS, ABBREVIATIONS and ACRONYMS
This section contains definitions of terms, abbreviations and acronyms needed for the proper
understanding and application of this standard, which are not believed to be adequately treated elsewhere.
                                                                                                               Formatted: German (Germany)
4.1         Definitions

4.1.1              Alternate Mark Inversion (AMI)
A line code that employs a ternary signal to convey binary digits, in which successive binary ones are
represented by signal elements that are normally of alternating positive and negative polarity and of equal
amplitude, and in which binary zeros are represented by signal elements that have zero amplitude. North
American implementations use signal elements representing binary ones that are non-zero for only half
the unit interval (50% duty cycle).

4.1.2              Bipolar violation (BPV)
A non-zero signal element in an AMI signal that has the same polarity as the previous non-zero element.

4.1.3              Channel
A channel is defined as one or more digital time-slots established to provide a communications path
between a message source and its destination. For the case when the 192 payload bits represent twenty-
four 8-bit channel time slots, making up 24 individual 64 kbit/s (DS0) bit streams, and each DS0 is
referred to as a DS0 channel.

4.1.4              Channelized
A DS1 frame is said to be channelized if the payload digit time slots are assigned in a fixed pattern to
signal elements from more than one source, each operating at a slower digital rate.

4.1.5              Clock accuracy
The maximum magnitude of fractional frequency offset from the ideal frequency for a specified time
period. Accuracy is usually used to define the frequency deviation of a clock in free-running mode.

4.1.6              Clock free running mode
In such a mode, the private network node works with its own clock source which is not locked to an
external reference and is not using storage techniques to maintain its accuracy.

4.1.7              Complete loopback
A loopback that operates on the full bit stream. At the loopback point, the received bit stream shall be
transmitted back towards the transmitting station without modification of the logical content of the signal.

4.1.8              Digital time slot
A time slot allocated to a single binary digit.

4.1.9              Digital Signal level 0 (DS0)
A digital signal transmitted at the nominal rate of 64 kbit/s.

4.1.10             Digital Signal level 1 (DS1)
A digital signal transmitted at the nominal rate of 1544 kbit/s.
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4.1.11            Hold-in range / Pull- iIn range
The largest offset between a slave clock’s reference frequency and a specified nominal frequency, within
which the slave clock maintains lock as the frequency varies arbitrarily slowly over the frequency range.

4.1.12            Line loopback
A complete loopback in which the signal returned toward the source of the loopback command consists of
the full 1544 kbit/s signal with (a) bit sequence integrity maintained, (b) no change in framing, and (c) no
removal of bipolar violations.

4.1.13            Master clock
A generator that generates an accurate frequency signal for the control of other generators.

4.1.14            NCTE/CSU loopback
A complete, transparent line loopback, located in the NCTE or CSU in the customer installation and
immediately in front of the network installation, in which the full 1544 kbps bit stream is returned
towards the source. The NCTE/CSU loopback can only be activated from with the customer installation.

4.1.15            Phase Lock Loop (PLL)
A feedback – controlled system that locks a local clock to an incoming reference clock in both frequency
and phase.

4.1.16            Primary Reference Source (PRS) or Clock (PRC)
Equipment that provides a timing signal, with a long term accuracy equal or better than 10-11 with
reference to Coordinated Universal Time (UTC) and whose timing signal may be used as the basis of
reference for the control of other clocks within a network.

4.1.17            Reference Clock
Timing signal used for synchronization, without any assumption on its accuracy.

4.1.18            Slave clock
Slave clock is a clock whose output signal is phase locked to a reference signal that is in synchronization
with or whose clock source is traceable to master clock.

4.1.19            Slip / Controlled Slip
It consists of the repetition or deletion of an integer number of octets caused by the elastic buffer
mechanism used at the interface of a non-synchronous bit stream (a plesiochronous or asynchronous one).
Slips and controlled slips shall be considered synonymous in this Standard.

4.1.20            Synchronization
The process of adjusting the corresponding significant instants of signals so that a constant phase
relationship exists between them.
                                                                                                               Formatted: Highlight
4.1.21            T1                                                                                           Formatted: Highlight
T1 is the first level of North America T-carrier system digital hierarchy. It transmits DS-1 formatted         Formatted: Highlight
signal at the nominal rate of 1544 kbps.
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4.1.221           Timing Loop
An unstable condition in which two or more equipment clocks transfer timing to each other, forming a
loop without a designated master timing source.

4.1.232           Unit Interval (UI)
The nominal difference in time between consecutive significant instants (e.g., zero level crossings) of an
isochronous signal.
                                                                                                             Formatted: Highlight
4.1.24            Voice Gateway Definition                                                                   Formatted: Heading 3
A device which routes packetized voice from one end-point to another, and provides other voice related
functions that a data gateway would not provide, e.g., voice coding and/or compression and echo
cancellation.
Its function is analogous to a PBX in that it provides connectivity between customer premise voice
terminals. It may provide interfaces to analog and digital (TDM and IP) voice terminals, and access to
both public and private WANs and public and private switched telephone networks.


4.2         Abbreviations and Acronyms
Abbreviations and acronyms, other than in common usage, which appear in this standard are defined
below.
ACTA        Administrative Council for Terminal Attachments
ANSI        American National Standards Institute
AIS         Alarm indication signal
AMI         Alternate Mark Inversion
BER         Bit error rate
BPV         Bipolar violation
CCC         Clear channel capability
CRC         Cyclic redundancy check
CSU         Channel service unit
FCC         Federal Communications Commission
LAPD        Link access procedure on the D channel
LBO         Line buildout network
LOF         Loss of frame
LOS         Loss of signal
                                                                                                             Formatted: English (United States)
ITU         International Telecommunication Union
MUX         Multiplexer
NCTE        Network Channel Terminating Equipment
NPRM        Network performance report message
OOF         Out-of-frame
PLL         Phase Locked Loop
PRS         Primary Reference Source
PISN        Private Integrated Services Network
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ppm     Parts per million
PSTN    Public Switched Telephone Network
RAI     Remote alarm indication
SAPI    Service access point identifier
SPRM    Supplementary performance report message
SES     Severely Errored Second
SONET   Synchronous Optical Network
                                                                                  Formatted: Highlight
T1      1.544 Mbits/s aAccess to public and private ISDNnetwork
UI      Unit interval
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5             DS1 and DSX-1 NETWORK INTERFACE REQUIREMENTS

5.1           Electrical and Physical Characteristics
This section specifies the electrical and physical characteristics of the packet-basedVoIP gateway 1544
kbps network interface, both at the DSX-1 interface when terminated by a limited function Network
Channel Terminating Equipment (NCTE) or DSX-1 compatible equipment, and at the DS1 interface
when not terminated by an NCTE. The DS1 interface is equivalent to the interface between the DS1
facility and the NCTE. When the DS1 line is connected to the DS1 interface, the packet-basedVoIP
gateway terminates the DS1 line and provides the necessary critical interface circuit functions to keep the
DS1 line working properly. The packet-based VoIP gateway shall provide a connection plug or jack
specified in T1 Technical Report No.5 for 1544 kbps access lines (Ref 16). Connections to the DSX-1
interface and to the DS1 interface are shown in Figure 1.
                                                                                                                       Formatted: Highlight
The requirements for 1544 kbps facilities are based on those of a standard T1 carrier. The line code is
either Alternate Mark Inversion (AMI) with Zero Code Suppression (ZCS) or Bipolar Eight Zero
Substitution (B8ZS). The legacy Alternate Mark Inversion (AMI) with Zero Code Suppression (ZCS) is                     Formatted: Highlight
not covered in this standard.                                                                                          Formatted: Highlight
AMI is old coding it should not be recommended, need to recommend B8ZS for new data technology.


                                  DSX-1 *                                                  Network
                                Cross-connect                                         **   Interface


              T                                                                                   T

DSX-1*        R                                                                                   R
Packet
VoIPBas                   DS1                   DS1         NCTE or CSU         DS1                         DS1
              T1                                            ANSI T1.403                           T1
ed
                                                              (Ref 2)
Gateway       R1                                                                                  R1




              T                                                                                   T

              R                                                                                   R
DS-1*
PacketVoI                 DS1                                                                               DS1
P Based       T1                                                                                  T1
Gateway
              R1                                                                                  R1



Notes:
      1.      *Electrical Characteristics are defined at this point (see 5.2.1, 5.2.2)
      2.      **Electrical Characteristics at the Network Interface are defined in ANSI T1.403-1999,
              Network and Customer Installation Interfaces - DS1 Electrical Interface (Ref 2)
      3.      NCTE/CSU is described in ANSI T1.403-1999, Network and Customer Installation Interfaces
              - DS1 Electrical Interface (Ref 2)


            Figure 1 - Packet-basedVoIP Gateway 1544 kbps Network Interface Connections
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5.2          Electrical Interfaces
5.2.1                 DSX-1 Electrical Interface
The electrical specifications describe the DSX-1 interface and, at the DSX-1 cross-connect interface, the
characteristics of the signals received from and transmitted to the DS1 facility. The signal delivered by
the facility is received on the T1 and R1 leads at the interface (Figure 1). The signal delivered by the
packet-basedVoIP gateway to the interface is transmitted on the T and R leads. The terms transmit and
receive are used to refer to signals from the perspective of the packet-based VoP gateway.
The requirements for the packet-basedVoIP gateway electrical interface are summarized below:

                    1544 kbps ±32 ppm (±50 b/s). The tolerance is for operating without any                  Formatted: Highlight
Line Rate:
                    synchronization to a network clock (e.g., self-timed, free-running). During
                    synchronized operation, the line-rate accuracy shall be as specified in
                    ANSI/TIA-594-B (Ref 8) and ANSI T1.101 (Ref 7) for the appropriate stratum
                    level.
                     Add ref. to TIA standard our group wrote on synchronization                            Formatted: Not Strikethrough, Highlight
                                                                                                             Formatted: Highlight
Line Code:          Alternate Mark Inversion (AMI) or B8ZS. (See text for pulse density
                    constraints.)  AMI is old coding it is recommend in data networks.                      Formatted: Highlight
                                                                                                             Formatted: Highlight
Test Load:          Resistive termination of 100  ± 5%.100  resistive ± 5%
                                                                                                             Formatted: Highlight
Pulse Amplitude     The amplitude of an isolated pulse shall be between 2.4 V and 3.6 V.have a base-
                                                                                                             Formatted: Highlight
                    to-peak amplitude between 2.4 V and 3.6 V.
                                                                                                             Formatted: Highlight
Pulse Shape:        An isolated pulse shall fit the template shown in Figure 2 at the cross-connect
                    point. An isolated pulse is defined as a pulse preceded by at least four zeros, and      Formatted: Highlight

                    followed by at least one or more zeros.                                                  Formatted: Highlight

                    For an all “-ones” transmitted pattern, the power in a 3 ± 1 kHz band centered at        Formatted: Highlight
Power Levels:
                    772 kHz shall be in the range 12.6 to 17.9 dBm. The power in a 3 ± 1 kHz band            Formatted: Highlight
                    centered at 1544 kHz shall be at least 29 dB less thanbelow that at 772 kHz.             Formatted: Highlight
                     This levels is incorrect for DSX-1, need to consolidate the statement from             Formatted: Highlight
                    below in this table .. …6 dB…                                                            Formatted: Highlight
Pulse Imbalance: In any window of 17 consecutive bits, the maximum variation in pulse                        Formatted: Highlight
                 amplitudes shall be less than 200 mV, and the maximum variation in pulse                    Formatted: Highlight
                 widths (half amplitude) shall be less than 20 ns.In any window of 17 consecutive
                                                                                                             Formatted: Highlight
                 bits, the maximum variation in pulse amplitudes shall be less than 200 mV and
                 the maximum variation in pulse width at half amplitude shall be less than 20 ns.            Formatted: Highlight
                                                                                                             Formatted: Highlight

Figure 2 presents the DSX-1 pulse template. Note that the corner points and the template shown in Figure
2 are normalized. The actual midpoint amplitude of the pulse at the cross-connect point can be between
2.4 V and 3.6 V. The electrical interface is based on the DSX-1 specification; i.e., equipment designed
for operation with DS1 facility losses of up to 6 dB at 772 kHz. For example, using 22 gauge ABAM
type cable, which has a loss of 6 dB at 772 kHz for 200 meters (655 feet), the distance between the DSX-
1 interface in the packet-basedVoIP gateway and a cross-connect point can be up to 200 meters (655 feet).
The distance from the cross-connect point to the DSX-1 interface in an NCTE for this example can also
be up to 200 meters (655 feet). Thus, a maximum separation (based on DSX-1 connectivity) of 400
meters (1310 feet) is possible in this example.
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        Norm alized Amplitude
            1.5



                                                           Maximum
              1                                              curve




            0.5




              0

                                                                          Minimum
                                                                            curve

           -0.5
                   -1           -0.5             0             0.5           1         1.5
                                           Tim e in Unit Intervals

Note: 1 Unit Interval = 648 nanoseconds




                                DSX-1 Pulse Template Corner Points
                          Minimum Curve                         Maximum Curve
                       Time            Normalized           Time          Normalized
                  (Unit Intervals)     Amplitude       (Unit Intervals)   Amplitude
                        -0.77            -0.05               -0.77           0.05
                        -0.23            -0.05               -0.39           0.05
                        -0.23             0.50               -0.27           0.80
                        -0.15             0.95               -0.27           1.15
                        0.00              0.95               -0.12           1.15
                        0.15              0.90               0.00            1.05
                        0.23              0.50               0.27            1.05
                        0.23             -0.45               0.35            -0.07
                        0.46             -0.45               0.93            0.05
                        0.66             -0.20               1.16            0.05
                        0.93             -0.05
                        1.16             -0.05
Successive corner points are joined by straight lines to form the template shown above

                    Figure 2 - DSX-1 Cross-Connect Isolated Pulse Template
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5.2.2                  DS1 Electrical Interface
The electrical specifications describe the characteristics of the signals received and transmitted to the DS1
facility at the DS1 packet-basedVoIP gateway interface (Figure 1). The signal delivered by the T1 carrier
is received on the packet-basedVoIP gateway T1 and R1 leads. The signal delivered by the packet-
basedVoIP gateway to the T1 carrier is transmitted on the T and R leads. The characteristics of the
signals at the DS1 packet-basedVoIP gateway interface are not symmetrical; i.e., some of the electrical
requirements differ for the transmit and receive signals. The terms transmit and receive are used to refer
to signals from the perspective of the packet-basedVoIP gateway.
The requirements for the electrical interface are summarized below:

Line Rate:          1544 kbps ±32 ppm (±50 b/s). The tolerance is for operating without any                     Formatted: Not Strikethrough

                    synchronization to a network clock (e.g., self-timed, free-running).           During
                    synchronized operation, the line-rate accuracy shall be as specified in ANSI/TIA-594-
                    B (Ref 8) and ANSI T1.101 (Ref 7) for the appropriate stratum level.Network Timed:
                      1544 kbps ±32 ppm (±50 b/s) (Note 2)
                    VoIP gateway Timed: 1544 kbps ±32 ppm (±50 b/s)
                    Need to line this, in line with sect 5.2.1 DSX-1 etc ….


                     Add ref. to TIA standard our group wrote on synchronization                               Formatted: Not Strikethrough
                                                                                                                Formatted: Not Strikethrough

Line Code:          Alternate Mark Inversion (AMI) or B8ZS. (See text for pulse density constraints.)           Formatted: Highlight
                                                                                                                Formatted: Highlight
                     AMI is old coding it is recommend in data networks.
                                                                                                                Formatted: Highlight
Test Load:          Resistive termination of 100  ± 5%.                                                        Formatted: Highlight

Pulse amplitude     An isolated pulse transmitted from the Network to the packet-basedVoIP gateway
                    shall have a base-to-peak amplitude between 2.25 V and 3.6 V. An isolated pulse
                    transmitted from the packet-basedVoIP gateway to the Network shall have a base-to-
                    peak amplitude between 2.4 V and 3.6 V.
Pulse Shape:        An isolated pulse shall fit the template shown in Figure 3. An isolated pulse is a pulse    Formatted Table

                    preceded by at least four zeros, and followed by at least one or more zeros. The shape
                    of an isolated pulse shall conform to the template shown in Figure 3. An
                    approximation of an isolated pulse is a pulse preceded by at least four zeros and
                    followed by at least one zero.
Power Levels:       For an all "ones" transmitted pattern, the power in a 3 ± 1 kHz band centered about
                    772 kHz shall be in the range 12.4 to 19.7 dBm. T and the power in a 3 ± 1 kHz band
                    centered about 1544 kHz shall be at least 25 dB less than the power measured at
                    772 kHz.
Pulse               In any window of 17 consecutive bits, the maximum variation in pulse amplitudes
Imbalance:          shall be less than 200 mV and the maximum variation in pulse width at half amplitude
                    shall be less than 20 ns.
60 Hz Pulse         Pulse amplitude may vary at a 60 Hz rate as a result of longitudinal currents in the
Amplitude           powering loops of T1 repeaters. In such cases, the envelope of the pulse amplitude
Variation:          shall be limited as shown in Figure 4. Any pulse amplitude in the ranges given above
                    may be used as the 100% point in Figure 4.
Notes:
    1.       The signal received by the packet-basedVoIP gateway at the network interface has the
             characteristics specified above, with the exception that the pulse characteristics will be those
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       of the standard signal transmitted through a cable pair with a loss in the range of 0.0 to 16.5
       dB at 772 kHz into a 100  termination. The lower limit of the standard pulse amplitude
       shall be 2.25 V rather than 2.4 V.
2.     Older equipment may have rate variations up to ± 128ppm (± 200 b/s).

          Norm alized Am plitude
           1.50


                                                             Maximum
                                                               curve
           1.00




           0.50




           0.00

                                                                             Minimum
                                                                               curve

          -0.50
                  -1.00          -0.50             0.00         0.50          1.00        1.50
                                             Tim e in Unit Intervals

Note: 1 Unit Interval = 648 nanoseconds




                                  DS1 Pulse Template Corner Points
                           Minimum Curve                         Maximum Curve
                   Time                  Normalized            Time          Normalized
              (Unit Intervals)           Amplitude        (Unit Intervals)   Amplitude
                      -0.77                -0.05               -0.77            0.05
                      -0.23                -0.05               -0.39            0.05
                      -0.23                 0.50               -0.27            0.80
                      -0.15                 0.90               -0.27            1.20
                          0.00              0.95               -0.12            1.20
                          0.15              0.90               0.00             1.05
                          0.23              0.50               0.27             1.05
                          0.23             -0.45               0.34             -0.05
                          0.46             -0.45               0.77             0.05
                          0.61             -0.26               1.16             0.05
                          0.93             -0.05
                          1.16             -0.05
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      Successive corner points are joined by straight lines to form the template shown below:

              Figure 3 - DS1 Packet-basedVoIP Gateway Interface Isolated Pulse Template
                                               1/60Hz = 16.7 ms
               110
               100


                75




     Pulse Amplitude
       (Percent of
       Reference)




               -75


               -100
               -110
                              0               5.3         8.3       11.3     14.3    16.7
                                                     Tim e (ms)

Notes:
1.      Envelope of pulse amplitudes shall lie within the shaded areas.
2.      Reference (100 percent point) may be any amplitude in the range of pulse amplitudes (see text).
                 Figure 4 - Pulse Amplitude Envelope with 60 Hz Longitudinal Currents


5.2.2.1                 Line Build Out (LBO) Networks
To ensure that a usable DS1 signal is available to the public and private network, selectable artificial
lines, or equivalent losses, shall be included in the transmit direction as part of the packet-basedVoIP
gateway interface circuitry. As a minimum, selectable values of 0.0, 7.5, and 15.0 dB of loss at 772 kHz
shall be available. The loss introduced by the packet-basedVoIP gateway LBO network shall not be flat.
It should have the frequency characteristics similar to those of twisted-pair cable. Examples of such
characteristics are found in Annex H of T1.403-1999, Network and Customer Installation Interfaces -
DS1 Electrical Interface (Ref 2).
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5.2.2.2               Powering Arrangements
The packet-basedVoIP gateway shall not apply any power (except signal power) to the network interface.
For some T1 carriers’ digital span lines, power is simplexed from a 60 mA constant current source at -         Formatted: Highlight
130Vdc from the carrier’s office and looped back by the circuitry of the packet-basedVoIP gateway DS1
interface. When this simplex current is provided at the network interface, the critical interface functions
may be powered by the simplexed current. The total simplexed power at the DS1 interface shall not
exceed 4 watts and should not exceed 1.5 watts.
The packet-basedVoIP gateway may provide local power for the critical interface circuitry. In any case,
the packet-basedVoIP gateway shall not cause the DS1 line to oscillate if the packet-basedVoIP gateway
experiences a power failure or is disconnected.
5.2.3                 Impedance Matching
The characteristic impedance of exchange cables used to provide DS1 service is nominally 100  at
772 kHz. To assure that performance objectives are met, this impedance should be matched by the
packet-basedVoIP gateway at the DSX-1 or DS1 interface.
5.2.4                 Longitudinal Balance
To ensure proper operation, longitudinal balance of the packet-basedVoIP gateway interface circuitry, in
the transmit and receive paths, shall be greater than 35 dB from 50 kHz to 1.544 MHz for each path.
5.2.4.1               Pulse Density Constraints
The pulse density of a DSX-1 or DS1 signal, except for the quasi-random signal, at the VoIP gateway
interface shall conform to the following constraints:
    (1)     In each window of 8 (n+1) bits, where "n" can equal 1 through 23, there shall be at least n
            "ones" present.
    (2)     No more than 15 consecutive "zeros."
5.2.5                 Synchronization Requirements
A packet-basedVoIP gateway connected to the public network by DS1 signals shall be synchronous to the
public network timing reference; either by using a DS1 signal received from the public network as its
reference for timing all outgoing DS1 signals, or by providing an equivalent accuracy of signal frequency.
Public network synchronization rules and definitions are given in ANSI T1.101-1999, Synchronization
Interface Standards for Digital Networks (Ref 7). Requirements for private network synchronization are
given in ANSI/TIA-594-B, Synchronization Methods and Technical Requirements for PISN (Ref 8).
5.2.5.1               Jitter and Wander
Jitter is short-term variation of the significant instants of a DSX-1 or DS1 signal from its ideal positions
in time. Wander is long-term variation of the significant instants of a DSX-1 or DS1 signal from its ideal
positions in time and applies when the timing is traceable to a primary reference source. The boundary
between long-term and short-term variation is 10 Hz. The magnitudes of jitter and wander are specified
in terms of unit intervals (UI) for three frequency bands. One UI is equal to 648 ns (one pulse period).
The frequency bands are:
    (1)     Band 1 (Jitter):     10 Hz to 40 kHz.
    (2)     Band 2 (Jitter):     8 kHz to at least 40 kHz.
    (3)     Band 3 (Wander): 0 to 10 Hz.
The weighting function for Band 1 is shown in Figure 5 and the weighting function for Band 2 is shown
in Figure 6.
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5.2.5.2                   Packet-basedVoIP gateway Output Signal Jitter
The jitter of the packet-based VoIP gateway output signal, at the interface to the PSTN, shall not exceed
the following limits, in both bands simultaneously:
      (1)      Band 1: 5.0 UI, peak-to-peak.
      (2)      Band 2: 0.1 UI, peak-to-peak.
The packet-basedVoIP gateway may not be connected directly to the PSTN, depending on whether or not
the Channel Service Unit (CSU) functionality is incorporated into the packet-basedVoIP gateway. An
external CSU that complies with T1.403 should not amplify any packet-basedVoIP gateway output jitter.
Therefore the above requirements would also apply to a packet-basedVoIP gateway connected to the
PSTN via a CSU.
Tandem packet-basedVoIP gateways in a private network may require more stringent limits on output
jitter if they do not provide jitter attenuation. Historically the following limits have been recommended to
prevent clock instability in large networks. These limits are only provided as guidelines, and it is up to
the individual manufacturers to determine the applicable limits for their systems.
      (1)      Band 1: 0.5 UI, peak-to-peak.
      (2)      Band 2: 0.07 UI, peak-to-peak.
5.2.5.3                   Packet-basedVoIP gateway Output Signal Wander
At the network interface, the wander of the packet-basedVoIP gateway signal shall not exceed the
following limits:
      (1)      Band 3 (Wander): 13 UI, peak-to-peak, in any 15 minute interval.
      (2)      Band 3 (Wander): 28 UI peak-to-peak, over any 24 hour period.
5.2.5.4                   Packet-basedVoIP gateway Jitter and Wander Input Tolerance
The packet-basedVoIP gateway shall accept signals at the network interface with the following jitter and
wander characteristics (simultaneously in Band 1 and Band 2):
      (1)      Band 1 (Jitter):      5.0 UI peak-to-peak.
      (2)      Band 2 (Jitter):      0.1 UI peak-to-peak.
      (3)      Band 3 (Wander): 13 UI, peak-to-peak, in any 15 minute interval.
      (4)      Band 3 (Wander): 28 UI peak-to-peak, over any 24 hour period.
5.2.5.5                   Packet-basedVoIP gateway Input Phase Transient Tolerance
The DS1 timing signal received from the network may experience phase transients, which are relatively
short duration step functions of the same instants. Many independent mechanisms (e.g., clock switching,
T1 protection switching, SONET VT pointers) can contribute to DS1 phase deviation in the public
network.
The duration of phase transients caused by clock switching depends upon the clock stratum level
involved. A stratum 4 may have a transient that has a duration in the range of milliseconds to seconds,
while a stratum 2 transient may take hours. The duration of phase transients due to SONET pointer
adjustments is presently undefined, but is expected to be on the order of seconds. Phase transients are
specified by maximum phase deviation (in UIs), and by maximum frequency off-set during the transient.
At the network interface, during the phase transient, the phase deviation shall not exceed 1.5 UI (1 s)1,
and the frequency of the signal shall not be offset from the nominal frequency by more than 61 ppm.
Such transients shall be isolated in time. The scope and details of phase transient specifications are


1   These transients are typically due to network clock rearrangements.
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expected to evolve in the future. In any case, phase slope characteristics of phase transients due to pointer
adjustments will be no greater than 61 ppm.
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             0

                                                        Slope: 20 dB/decade


    Weighting
      (dB)



                                            10 Hz                                      40 kHz
                                                                       Band 1




                                               Frequency (Log Scale)
  Note:     40 kHz represents the upper limit for Band 1 cutoff frequency based on currently available
            test equipment.
             Figure 5 - Frequency Weighting Function for Band 1 Jitter Specification




       0


                                                     Slope: 20 dB/decade

Weighting
  (dB)



                                       8 kHz                                       40 kHz
                                                                 Band 2




                                               Frequency (Log Scale)
  Note:     40 kHz represents the upper limit for Band 2 cutoff frequency based on currently available
            test equipment.
             Figure 6 - Frequency Weighting Function for Band 2 Jitter Specification
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5.2.6                  Clear Channel Capability
Bipolar Eight Zero Substitution (B8ZS) provides clear channel capability at the DSX-1 or DS1 interface.
5.2.6.1                B8ZS Encoding
When B8ZS coding is used, "ones" density is obtained without altering data. B8ZS coding replaces any
eight consecutive zeros of the DSX-1 or DS1 signal with the pattern shown in Figure 7 and discussed
below.
With B8ZS coding, each group of eight consecutive zeros is removed and the B8ZS code is substituted.
If the pulse preceding the inserted code is transmitted as a positive pulse (+), the inserted code is 000+-0-
+. If the pulse preceding the inserted code is a negative pulse (-), the inserted code is 000-+0+-. In both
cases, bipolar violations occur in the fourth and seventh bit positions of the inserted code. B8ZS coding
is done at the 1544 kbps level; i.e. framing bits are included in the coding.
5.2.6.1.1                Decoding B8ZS Signals
To decode B8ZS coded signals, the receiver shall continuously monitor the incoming DS1 signal for
B8ZS code words. When a B8ZS code word is detected, it shall be replaced by eight zeros. Note that
when a DS1 signal is coded using B8ZS, bipolar violations that are detected due to zero substitution
should not be used in error rate calculations.
5.2.6.1.2                Transmitting B8ZS Coding
An end-to-end clear DS1 network-provided path is possible when both access facilities and all intervening
facilities are clear. Equipment meeting this specification should incorporate B8ZS coding but include the
capability for disabling it when interfacing network facilities that do not support clear channels.


 Uncoded
 Bit Stream      010011          00000000            111        00000000                00000000        01

          Time


 Pulse
 Stream          0+00 - +        000+ - 0 - +         -+-       000 - +0+ -             000 - +0+ -     0+




                                                         Violations Based on Polarity
                                                             of last 1 transmitted

                    Figure 7 - Example of Bipolar Eight Zero Substitution (B8ZS)
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5.2.6.2                    Zero Code Suppression
For applications where B8ZS coding cannot be used, Zero Code Suppression as shown in Figure 8 may
be provided. This is done by detecting an all zero octet in a channel and substituting at least one "1" for a
"0" somewhere in the octet. For example, a "1" could be placed in the second least significant bit position
(bit 7) before AMI coding. Framing bits are not included in Zero Code Suppression. Zero Code
Suppression is performed on a per-channel basis so that adjacent channels are not affected by a channel
that is violating the “ones” density constraints.
 This section ZCS recommend to delet it since AMI is not recommended in packet networks.
                                                                                                                Formatted: Normal

                                  Channel n-1        Channel n        Channel n+1

          Uncoded Bit          01001100            00000000         11100000
          Stream


          Zero Code
          Suppression Done
                                                   00000010
          Prior to DS-1 Line
          Coding
                                                                                        Forced "1" in
                                                                                        2nd least
                                                                                        significant bit
                                                                                        position
          AMI Pulse Stream     0+00 - +00          000000 - 0       + - +00000
          at DS-1 Level
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      Note:     The framing bit is not included in the bit stream to be processed under ZCS. In addition, the
                octets examined for all zeros must be aligned with channel octets.
                    Figure 8 - Example of Alternate Mark Inversion with Zero Code Suppression

5.3             Signal Formats
                                                                                                                                Formatted: Highlight
For 1544 kbps applications, two framing formats are supported:
(1)         The Superframe Framing (SF) format used by the D4 member of the D-channel bank family.                              Formatted: Indent: Left: 0", First line: 0"

(2)         The Extended Superframe Framing (ESF) format is.
 Should recommend ESF for all interfaces                                                                                       Formatted: Highlight
                                                                                                                                Formatted: Highlight
Both formats are specified in ANSI T1.107-1995, Digital Hierarchy - Formats Specification (Ref 9).
                                                                                                                                Formatted: List1, Space Before: 0 pt, Tab
All 1544 kbps implementations supporting ESF framing shall also have the capability of supporting SF                            stops: Not at 0.13"
framing if the public and private network provided transmission systems are to be used.
                                                                                                                                Formatted: List1, Tab stops: Not at 0.13"
The SF and ESF does not in themselves impose restrictions on the use of the 192 information bits within a
frame. The customer may use the information bits as required, unless the line is to interface a digital
channel bank or other central office equipment that requires specific bit assignment within the frame.
Regardless of the framing format used, the following conditions shall be met for 1544 kbps facilities:
      (1)       The maximum average reframe time shall be less than 50 milliseconds in the absence of
                errors (maximum average reframe time is the average time to reframe when the maximum
                number of bit positions must be examined for the framing pattern).
      (2)       Framing shall be declared to be lost when framing bits are in error in the range of two of four,
                two of five, or three of five for a period greater than or equal to 2 seconds, and less than or
                equal to 10 seconds.
5.3.1                       Frame
The DSX-1 or DS1 frame shall conform with the requirements specified in ANSI T1.107-1995, Digital
Hierarchy - Formats Specification (Ref 9).
5.3.1.1                     Frame Structure
The frame consists of 24 eight bit words (octets) and one frame bit for a total of 193 bits per frame, as
shown in Figure 98. The nominal bit rate of the outgoing DSX-1 or DS1 signal is 1544 kbps, and the                              Formatted: Highlight
frame repetition rate is 8 kHz.


                                                            1 Frame
                                                        125 s, 193 Bits


                                                                                      Time
                            1                                     2                   Slot #                   24


      F     1   2   3   4       5   6   7   8   1   2    3    4       5   6   7   8   Bit #    1   2   3   4    5   6   7   8
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    Sampling Frequency:         8000 Hz
    Output Bit Rate:            1544 kbps
    Bits/Frame:                 193
    Time Slots/Frame:           24 (Sequential Assignment)
                                Figure 89 - 1544 kbps Signal Format


5.3.1.2               Channel Numbering
Channels are numbered sequentially from 1 to 24 in the order that they are presented to a receiver.
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5.3.2                 Superframe Format
In the Superframe Framing format, the frame bit is time shared to identify both channel framing and
signaling channel framing as shown in Figure 10. Both channel framing and signaling framing identify
the location of time slot one and signaling framing identifies those frames in which signaling channels A
and B are normally transmitted when using robbed bit signaling.


              Frame         Bit         F Bit    Information      Signaling     Signaling
             Number       Number                 Coding Bits         Bit        Channel
                                      FS   FT
                1            0         -    1         1-8              -
                2           193        0    -         1-8              -
                3           386        -    0         1-8              -
                4           579        0    -         1-8              -
                5           772        -    1         1-8              -
                6           965        1    -         1-7             8             A
                7          1158        -    0         1-8              -
                8          1351        1    -         1-8              -
                9          1544        -    1         1-8              -
                10         1737        1    -         1-8              -
                11         1930        -    0         1-8              -
                12         2123      0    -        1-7                8             B
            FS - Signaling Channel Framing (Sequence ...001110...)
            FT - Terminal Framing (Sequence ...101010...)
                                 Figure 10 - Superframe Framing Format


5.3.3                 Extended Superframe Framing Format
                                                                                                            Formatted: Highlight
As an option to the use of the Superframe Framing format, Tthe Extended Superframe Framing format
(ESF) may be used. ESF will replace the earlier SF format as the standard for DS1 level framing in North    Formatted: Highlight
America. The ESF format is described in Ref 2. It is planned for implementation in all new designs of       Formatted: Highlight
DS1 level equipment that frame on a pattern contained within the framing bit position of the DS1 1544       Formatted: Highlight
kbps signal. ESF framing is not compatible with SF framing.                                                 Formatted: Highlight
The ESF framing format "extends" the DS1 superframe structure from 12 frames (2316 bits) to 24 frames       Formatted: Highlight
(4632 bits) and redefines the 8 kb/s framing bit position. The 8 kb/s ESF channel is divided into 2 kb/s
for channel framing and signaling channel framing, 2 kb/s for a Cyclic Redundancy Check code (CRC-6),
and 4 kb/s for a data link. The ESF also supports multiple state signaling.
5.3.3.1               2 kb/s Framing Pattern
                                                                                                            Formatted: Highlight
As shown in Figure 811, beginning with frame 4 (Extended Superframe bit 579), the framing bit of every
fourth frame forms the pattern 001011. . .001011. This pattern is used to determine channel and signaling   Formatted: Highlight
channel synchronization. Frame synchronization is used to locate the 24 DS0 channels in each frame.
Superframe synchronization is used to identify where each particular frame is located within the
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superframe to perform the CRC-6 checks and identify the relationship of signaling information to DS0
channels.
5.3.3.2               2 kb/s Cyclic Redundancy Check, CRC-6
The cyclic redundancy check code, CRC-6 is a method of performance monitoring that is contained
within the F-bit position of frames 2, 6, 10, 14, 18, and 22 of every superframe (see Figure 11. The CRC-      Formatted: Highlight
6 code has the ability to detect most errors that occur on the DS1 signal and can be used in various
applications such as false framing protection, protection switching, performance monitoring, and line
verification before, during, and after maintenance. The CRC-6 is capable of detecting 63/64 (98.4%) of
all CRC Message Blocks (CMBs) containing transmission errors. It does not give an indication of the
number of errors in a CMB, only that there was at least one.
The CRC-6 message block check bits CB1, CB2, CB3, CB4, CB5, and CB6 are contained within the
Extended Superframe (ESF) format bits 193, 965, 1737, 2509, 3281, and 4053 respectively, as shown in
Figure 911. The CRC-6 Message Block (CMB), shown in Figure 102, is a sequence of 4632 serial bits              Formatted: Highlight
that is coincident with an ESF. By definition, CMB N begins at bit position 0 of ESF N and ends with bit       Formatted: Highlight
4631 of ESF N. The first transmitted bit of a CMB is the most significant bit of the CMB polynomial.
For the purpose of generating the CRC-6 sequence, each F-bit position in the CMB should be set to a
binary one. That is, the information in the F-bit position will have the value "1" in the calculation of the
CRC-6 bits. All information in the other bit positions will be identical to the information in the
corresponding ESF bit positions.
The Check-Bit sequence CB1 through CB6 transmitted in ESF N+1 is the remainder after multiplication
by the polynomial X6 and then division (Modulo-2) by the generator polynomial X6 + X + 1 of the
polynomial corresponding to CMB N. The first check bit (CB1) is the most significant bit of the
remainder; the last check bit (CB6) is the least significant bit of the remainder. Each ESF contains the
CRC-6 check bits generated for the preceding CMB.
At the transmitter, the initial remainder of the division for each CMB is preset to all zeros and is then
modified by division by the generator polynomial (as described above). The division is performed on
CMBs after the F-bits are set to a binary "1". The remainder bits should then be inserted into the check
bit positions of the subsequent ESF.
At the receiver, the initial remainder of the division for each received CMB is preset to all zeros and is
then modified by division by the generator polynomial. The resulting remainder is compared on a bit-by-
bit basis with the CRC-6 check bits contained in the subsequently received ESF. The compared check
bits will be identical in the absence of transmission errors.
A mathematical example of the generation of check bits is shown in Figure 113. For simplicity, a CMB
length of 10 bits has been used instead of the actual length of 4632 bits.
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   ESF        ESF Bit         F-Bit Assignment       Bit use in each 8-bit   Signaling Bit
  Frame       Number                                      Time Slot          Use Options
  Number
                         FPS       {F}DL    CRC      Traffic   Robbed-       T   Signaling
                                                                  bit            Channel
                                                               Signaling
     1           0        -          m           -    1-8          -
     2          193       -          -      CB1       1-8          -
     3          386       -          m           -    1-8          -
     4          579       0          -           -    1-8          -
     5          772       -          m           -    1-8          -
     6          965       -          -      CB2       1-7          8         -   A   A   A
     7         1158       -          m           -    1-8          -
     8         1351       0          -           -    1-8          -
     9         1544       -          m           -    1-8          -
    10         1737       -          -      CB3       1-8          -
    11         1930       -          m           -    1-8          -
    12         2123       1          -           -    1-7          8         -   A   B   B
    13         2316       -          m           -    1-8          -
    14         2509       -          -      CB4       1-8          -
    15         2702       -          m           -    1-8          -
    16         2895       0          -           -    1-8          -
    17         3088       -          m           -    1-8          -
    18         3281       -          -      CB5       1-7          8         -   A   A   C
    19         3474       -          m           -    1-8          -
    20         3667       1          -           -    1-8          -
    21         3860       -          m           -    1-8          -
    22         4053       -          -      CB6       1-8          -
    23         4246       -          m           -    1-8          -
    24         4439       1          -           -    1-7          8         -   A   B   D

FPS:        Framing Pattern Sequence (...001011...)
{F}DL:      4 kb/s {Facility} Data Link (message bits m)
CRC:        CRC-6 Cyclic Redundancy Check (check bits CB1-CB6)
Option T:   Traffic (Bit 8 not used for robbed-bit signaling)

                                                                                                     Formatted: Highlight
            Figure 119 - Extended Superframe Framing (ESF) F-Bit Assignments
                                                                                                     Formatted: Highlight
                                                                                                     Formatted: Highlight
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F-Bit use     CB6            m               1              M            CB1            CB6               m         1           m
F-Bit        4053           4246         4439               0            193            4053          4246          4439        0




Frame               22              23            24               1           2 - 21           22            23           24


                         ESF N-1                                                             ESF N


                         CMB N-1                                                          CMB N


                                         Figure 102 - ESF/CMB Relationship




                                   Divisor              Dividend (CMB * 106)
                            1 0 0 0 0 1 1 1 1 1 0 0 1 0 1 0 1 0 0 0 0 0 0
                                                 1 0 0 0 0 1 1
                                                   1 1 0 0 0 1 1
                                                  1 0 0 0 0 1 1
                                                    1 0 0 0 0 0 0
                                                       1 0 0 0 0 1 1
                                                         0 0 0 0 1 1 1
                                                            0 0 0 0 0 0 0
                                                              0 0 0 1 1 1 0
                                                                0 0 0 0 0 0 0
                                                                  0 0 1 1 1 0 0
                                                                 0 0 0 0 0 0 0
                                                                   0 1 1 1 0 0 0
                                                                   0 0 0 0 0 0 0
                                                                     1 1 1 0 0 0 0
                                                                        1 0 0 0 0 1 1
                                                                          1 1 0 0 1 1 0
                                                                         1 0 0 0 0 1 1
                                                                           1 0 0 1 0 1 0
                                                                           1 0 0 0 0 1 1
                                                       Remainder =           0 0 1 0 0 1

            Check Bits (Remainder) to be
                                                       CB1        CB2      CB3          CB4          CB5      CB6
            sent in CMB N+1:
                                                        0           0          1         0            0        1
                                   Figure 113 - Mathematical Check-Bit Generation
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5.3.3.3                 False Framing Protection
It is possible to couple the Cyclic Redundancy Check of the ESF framing format with the reframing
algorithms to insure that the valid framing pattern contained within the framing bit positions is the only
pattern the reframer can lock onto permanently. False framing protection could be implemented using the
ESF format as follows:
When the reframer sees more than one candidate for reframe, it locks onto the first candidate and then
checks the CRC-6 code. If this code indicates continuous errors, the reframer then searches for the next
available candidate, locks onto it, and then checks the CRC-6 code again.
5.3.3.4                 Data Link
Beginning with frame 1 (ESF bit 0) of the superframe (see Figure 11), every other 193rd bit is part of the
4 kb/s data link. The ESF data link (DL) is used to carry performance information and control signals
across the DS1 interface. The specification of these signals is the same for both directions of
transmission2.
Performance information appearing in one direction of transmission is a quantification of the quality of
transmission in the opposite direction.
Two signal formats are used on the DL:
    (1)       Bit-patterned signals: repeated patterns (codes).
    (2)       Message-patterned signals: messages using a Q.921 LAPD protocol.
The bit-oriented signals carry priority messages and command-and-response messages. The message-
oriented signals carry performance monitoring information. The structure of the information within the
message-oriented protocol is bit assigned. The monitored parameters for transmission error events are in
5.2.2.3.4.3; the formats of the generated bit-oriented messages are in 5.3.3.4.1.3 and those for message-
oriented messages are in 5.2.3.4.2.1
Operation, administration, and maintenance of the network may cause other messages to appear at the
DS1 interface (the packet-basedVoIP gateway should be able to disregard any such undefined messages).
Use of the DL for other terminal-to-network communications or for any terminal-to-terminal messages
beyond the described set is for future study. Network architecture is such that the DL may be
discontinuous relative to the DS1 payload, and end-to-end continuity of the DL cannot be guaranteed.
When idle, the DL shall contain continuous repetitions of the data link idle code - 01111110.
5.3.3.4.1                 Bit-Patterned Messages
Bit-oriented messages are pre-emptive. When sent, they overwrite other signals on the DL. Table 1 lists
two categories of bit-oriented messages ("priority" and "command and response") and the specific
functions associated with each.
5.3.3.4.1.1               Priority Messages
Priority messages indicate a service-affecting condition. They shall transmit continually until the
condition no longer exists, but, for not less than 1 s. These messages may be interrupted for a maximum
of 100 ms per interruption with a minimum interval of one second between interruptions.




2    Equipment that uses the data link exclusively for Yellow Alarm and for an “all-ones” idle code exists in the
     network and will continue to exist. The Yellow Alarm is a repeating 16-bit pattern of 8 "ones" followed by 8
     "zeros" (0000000011111111). This pattern is transmitted continuously for 256 ± 4 times or until the out-of-
     frame condition no longer exists, whichever is longer. Such equipment cannot take advantage of the standard
     features described in this section. Thus, when such equipment is connected to equipment that meets the
     specifications of this section, performance information and control signals appear in one direction only.
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5.3.3.4.1.2              Command and Response Messages
Command and response messages are transmitted to perform various functions. The loopback commands
of Table 1 activate and deactivate the line loopback and payload loopback functions of the packet-
basedVoIP gateway as described in 5.3.5. Command and response messages that are labeled "Reserved
for network use" shall not be generated by the packet-basedVoIP gateway. The use of the network
loopback and protection switching functions of Table 1 are not covered in this standard. Command and
response code words shall be repeated at least 10 times as a continuous transmission.
5.3.3.4.1.3              Format of Bit-Oriented Messages
Data link bit-oriented messages shall be of the format:
                                            0xxxxxx011111111
with the rightmost bit transmitted first. Table 1 lists two categories of bit-oriented message functions and
their associated 16-bit codewords. Table 2 lists unassigned codewords. Codewords for priority messages
shall be repeated continually until the condition that initiated the message is removed. The minimum
duration shall be as specified for Remote Alarm Indication in 5.3.4.1.4.
5.3.3.4.2                Message-Oriented Signals
Message-oriented signals are signals conforming to an HDLC protocol as defined below. Two message-
oriented signals are defined for the ESF data link. One is a periodic performance report generated by the
source/sink DS1 terminals. The other is a path, test, or idle signal identification message that may be
optionally generated by a terminal or intermediate equipment on a DS1 circuit.
5.3.3.4.2.1              Format of Message-Oriented Performance Report
To carry performance reports, the carrier signal and the packet-basedVoIP gateway signal shall conform
to the layer 2 protocol (LAPD) specified in ITU-T Recommendation Q.921, ISDN User-Network
Interface Data Link Layer Specification (Ref 10). This application shall use a subset of the full
capabilities of the Q.921/LAPD protocol. The message structure is shown in Figure 124, where the               Formatted: Highlight
following abbreviations are used:                                                                              Formatted: Highlight
    (1)       SAPI: Service Access Point Identifier.
    (2)       C/R: Command/Response.
    (3)       EA: Extended Address.
    (4)       TEI: Terminal Endpoint Identifier.
    (5)       FCS: Frame Check Sequence.
This message structure is that of a Q.921/LAPD unnumbered and unacknowledged frame.                     The
performance report shall use only the SAPI/TEI values shown in Figure 124.                                     Formatted: Highlight

The source of the performance report shall generate the Frame Check Sequence (FCS) and the zero                Formatted: Highlight
stuffing required for transparency. Zero stuffing by a transmitter prevents the occurrence of the flag
pattern (01111110) in the bits between the opening and closing flags of a Q.921/LAPD frame by inserting
a zero after any sequence of five consecutive ones. (A receiver removes a zero following five consecutive
ones.) The data elements in the performance report are arranged so that zero stuffing will never occur in
the information field. Thus, except for the FCS, the line signal duplicates the list sequence of the report,
and the message is of constant length from the opening flag to the end of the information field.
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Throughput of the data link may be reduced to less than 4 kb/s in some cases. The performance report is
always passed3.
5.3.3.4.2.2               Transmission Error Events
The occurrences of transmission error events indicate the quality of transmission. The occurrences that
shall be detected and reported are:
     (1)      No events
     (2)      CRC error
     (3)      Severely errored framing
     (4)      Frame synchronization bit error
     (5)      Line code violation
     (6)      Controlled slip
These are defined as follows:
     (1)      CRC Error Event - A CRC error event is the occurrence of a received CRC code that is not
              identical to the locally calculated code.
     (2)      Severely Errored Framing Event - A severely errored framing event is the occurrence of two
              or more framing bit pattern errors within a 3-ms period. Contiguous 3-ms intervals shall be
              examined. The 3-ms period may coincide with the ESF. This framing error indicator, while
              similar in form to criteria for declaring a terminal has lost framing, is only designed as a
              performance indicator; existing terminal out-of-frame criteria will continue to serve as the
              basis for terminal alarms.
     (3)      Frame Synchronization Bit Error Event - A frame synchronization bit error event is the
              occurrence of a received framing bit pattern error.
     (4)      Line Code Violation Event - A line code violation event for an AMI-coded signal is the             Formatted: Highlight

              occurrence of a received excessive zeros (EXZ) or a bipolar violation. A line code violation
              event for a B8ZS-coded signal is the occurrence of a received bipolar violation that is not part
              of a zero-substitution code. Some existing equipment may not detect EXZs.
     (5)      Controlled-Slip Event - A controlled-slip event is the occurrence of a replication or deletion
              of the data bits of a DS1 frame by the receiving terminal. A controlled slip occurs when there
              is a difference between the timing of a synchronous receiving terminal and that of the
              received signal of such magnitude as to exhaust the buffering capability of the synchronous
              terminal.
5.3.3.4.2.3               Message-Oriented Performance Report
The carrier signal and the packet-basedVoIP gateway signal shall include a performance report sent each
second using a bit-assigned message structure. The one-second timing may be derived from the DS1
signal or from a separate equally accurate (±32 ppm) source. The phase of the one-second periods with
respect to events is arbitrary; i.e., the one-second timing does not depend on the time of occurrence of any
error event.
The performance report contains performance information for each of the four previous one-second
intervals. This is shown in Figure 124, octets 5 through 12, and by an example in Table 3.                       Formatted: Highlight
                                                                                                                 Formatted: Highlight




3.   The performance report with SAPI 14 should be constructed and inserted on the data link by the source
     terminal that constructs the information payload of the DS1 signal. The performance report with SAPI 14
     should be delivered without alteration to the same terminal that sinks the information payload of the DS1
     signal.
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Counts of events shall be accumulated in each contiguous one-second interval. At the end of each one-
second interval, a modulo 4 counter shall be incremented, and the appropriate performance bits shall be
set in the t = 0 octets (octets 5 and 6 in Figure 124). These octets and the octets that carry performance
bits of the three preceding one-second intervals form the performance report.
5.3.3.4.3               Performance Sectionalization Messages
Performance sectionalization messages are intended for use in determining whether performance
degradations exist within the network, within the packet-basedVoIP gateway, or both.
From a public and private network perspective, Supplementary Performance Report Message (SPRM) or
Network Performance Report Message (NPRM) signals are detected by the carrier using intermediate
path monitoring either in a non-intrusive device or at a DCS or other DS1 line terminating equipment
with intermediate path monitoring capability.
Since the SPRM and NPRM are symmetric, and can be sent toward the packet-basedVoIP gateway as
well, the packet-basedVoIP gateway could also monitor these signals at the DS1 path termination.
The following two methods for performance sectionalization, SPRM and NPRM, can be employed on a
DS1 path in either direction:
    (1)     Supplementary Performance Report Message (SPRM)
            SPRM is intended for application at a point within the network to determine whether errors in
            the DS1 path originate in the network or in the packet-basedVoIP gateway. The R, U1 and
            U2 bits of the PRMs are used to carry the supplementary information.
    (2)     Network Performance Report Message (NPRM)
            NPRM is intended for application at a point within the network as close as is practicable to
            the network interface to determine whether errors in the DS1 path originate in the network or
            in the packet-basedVoIP gateway. NPRM messages contain information on the quality of
            transmission on both sides of the network interface.
5.3.3.4.4               Path and Test Signal ID Message(s)
Path and test signal identification messages are optional messages that may be sent on the ESF data link.
        One is used to identify the path between the source terminal and the sink terminal, and is referred
        to as a path ID (PID). The other is used by test signal generating equipment and is referred to as a
        test signal ID (TSID). If sent, they shall conform to the format and content requirements specified
        in ANSI Standard T1.403-1999 for telecommunications - Network and Customer Installation
        Interfaces - DS1 Electrical Interface, Annex A (Ref 2).
5.3.3.4.5               Special Carrier Applications
A carrier may require the use of the ESF data link for purposes related to the provisioning or maintenance
of the DS1 facility or circuit. Examples of these functions are:
    (1)     Communicating performance information within the Network.
    (2)     Providing protection switching control.
    (3)     Providing clear channel capability.
Such uses may cause interruptions, delays, or reduction of throughput on the ESF data link, but should
not impact the timely transmission of the bit-oriented messages and of the performance report. The
performance report shall always be passed.
5.3.3.4.6               DS1 Idle Code
Generation and detection of the DS1 idle signal is optional. If provided, the DS1 idle signal shall meet
the requirements defined in Annex C of ANSI T1.403-1999 (Ref 2). The idle signal indicates that the
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normal signal source is not present. The DS1 idle signal is not to be confused with the data link idle code
defined in 5.3.3.4.




  Octet #                                 Octet Label                                              Octet
                                                                                                  Content
             8        7        6          5           4    3        2         1
     1                             Flag                                                      01111110
                                                                                             00111000
     2                             SAPI                            C/R       EA                 or
                                                                                             00111010
     3                             TEI                                       EA              00000001
     4                                        Control
     5      G3       LV       G4          U1          U2   G5      SL        G6      t
                                                                                      0      
     6       FE      SE       LB          G1          R    G2      Nm        N1              
                                                                                              
                                                                                     t       
     7      G3       LV       G4          U1          U2   G5      SL        G6               
                                                                                      0-1    
                                                                                                    One-
     8       FE      SE       LB          G1          R    G2      Nm        N1               
                                                                                                   second
     9      G3       LV       G4          U1          U2   G5      SL        G6      t            Report
                                                                                      0-2    
                                                                                             
    10       FE      SE       LB          G1          R    G2      Nm        N1               
                                                                                              
    11      G3       LV       G4          U1          U2   G5      SL        G6      t       
                                                                                      0-3    
    12       FE      SE       LB          G1          R    G2      Nm        N1      

    13
    &                                          FCS                                            variable
    14
    15                                         Flag                                          01111110


                          Figure 124 - Performance Report Message Structure
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Address                          Interpretation
00111000                         SAPI=14, C/R=0 (CI) EA=0
00111010                         SAPI=14, C/R=1 (Carrier) EA=0
00000001                         TEI=0, EA=1



Control                          Interpretation
00000011                         Unacknowledged Information Transfer



One-second report                Interpretation
G1 = 1                           CRC Error Event = 1
G2 = 1                           1 < CRC Error Event < 5
G3 = 1                           5 < CRC Error Event < 10
G4 = 1                           10 < CRC Error Event < 100
G5 = 1                           100 < CRC Error Event < 319
G6 = 1                           CRC Error Event > 320
SE = 1                           Severely-Errored Framing Event > 1 (FE shall = 0)
FE = 1                           Frame Synchronization Bit Error Event > 1 (SE shall = 0)
LV = 1                           Line Code Violation Event > 1
SL = 1                           Slip Event > 1
LB = 1                           Payload Loopback Activated
U1, U2 = 0                       Under study for synchronization
R=0                              Reserved (Default value is 0)
NmNl = 00, 01, 10, 11            One-second report modulo 4 counter



FCS                              Interpretation
Variable                         CRC16 Frame Check Sequence


             Figure 124 - Performance Report Message Structure (continued)
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                 Table 1 - Assigned Bit-patterned ESF Data Link Messages

                    Function                                Codeword (Note 1)
                                     Priority Messages
Remote Alarm Signal (Yellow Alarm)                       00000000       11111111
Loopback retention                                       00101010       11111111
ISDN (international)                                     00011100       11111111

                              Command and Response Messages
Line Loopback Activate                                  00001110        11111111
Line Loopback Deactivate                                00111000        11111111
Payload Loopback Activate                               00010100        11111111
Payload Loopback Deactivate                             00110010        11111111
Reserved for network use (loopback activate)            00010010        11111111
Universal Loopback (deactivate)                         00100100        11111111
ISDN Loopback                                           00101110        11111111
ISDN Loopback                                           00100000        11111111
Protection Switch Line 1 (Note 2)                       01000010        11111111
Protection Switch Line 2                                01000100        11111111
Protection Switch Line 3                                01000110        11111111
Protection Switch Line 4                                01001000        11111111
  :        :                                                : :            : :
Protection Switch line 24                               01110000        11111111
Protection Switch line 25                               01110010        11111111
Protection Switch Line 26                               01110100        11111111
Protection Switch Line 27                               01110110        11111111
Protection Switch Acknowledge                           00011000        11111111
Protection Switch Release                               00100110        11111111
Don't use for Sync (Note 3)                             00110000        11111111
Stratum 2 traceable                                     00001100        11111111
±20 ppm clock traceable                                 00100010        11111111
Stratum 4 traceable                                     00101000        11111111
Stratum 1 traceable                                     00000100        11111111
Synchronization traceability unknown                    00001000        11111111
Stratum 3 traceable                                     00010000        11111111
Reserved for network sync                               01000000        11111111
Understudy for maintenance                              00101100        11111111
Understudy for maintenance                              00110100        11111111
Reserved for Network use                                00010110        11111111
Reserved for Network use                                00011010        11111111
Reserved for Network use                                00011110        11111111
Reserved for Network use                                00111010        11111111
Reserved for customer                                   00000110        11111111
Reserved for customer                                   00001010        11111111
Reserved for customer                                   00000010        11111111
Reserved for customer                                   00110110        11111111
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Notes on Table 1:
   (1)     Rightmost bit transmitted first.
   (2)     The "protection switch line" codes of the form 01XXXXX011111111 use the five bits
           designated X to contain the binary representation of the number of the line, 1 through 27, to
           be switched to a protection line (e.g., the code for line 25 is a 1 followed by 11001 which is
           the binary representation of 25).
   (3)     Use of this block of codewords is described in ATIS T1X1 Technical Report No. 33 (Ref 17).




                          Table 2 - Unassigned ESF Data Link Codewords

                                          Codeword (Note 1)
                                         00111100 11111111
                                         01111000 11111111
                                         00111110 11111111
                                         01111010 11111111
                                         01111100 11111111
                                         01111110 11111111           (Note 2)


Notes on Table 2:
   (1)     Rightmost bit transmitted first
   (2)     Assignment of this codeword should be avoided due to its similarity to the DL idle code
           described in 5.3.3.4
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               Table 3 - Example - ESF Data Link Performance Report Messages

Message sent at
  t = t0-3           Slip = 1, all other parameters = 0, NmN1 = 01
          t0-2       Severely-errored framing event = 1, all other parameters = 0, NmN1 = 10
          t0-1       CRC error events = 1, all other parameters = 0, NmN1 = 11
          t0         CRC error events = 320, all other parameters = 0, NmN1 = 00
          t0+1       CRC error events = 0, all other parameters = 0, NmN1 = 01
          t0+2       CRC error events = 6, all other parameters = 0, NmN1 = 10
          t0+3       CRC error events = 40, all other parameters = 0, NmN1 = 11


Specific octets              t=t0             t=t0+1           t=t0+2            t=t0+3

Flag                         01111110         01111110         01111110          01111110
Address octet 1              00111000         00111000         00111000          00111000
Address octet 2              00000001         00000001         00000001          00000001
Control                      00000011         00000011         00000011          00000011


Message octet 1              00000001         00000000         10000000          00100000
Message octet 2              00000000         00000001         00000010          00000011


Message octet 3              00000000         00000001         00000000          10000000
Message octet 4              00010011         00000000         00000001          00000010


Message octet 5              00000000         00000000         00000001          00000000
Message octet 6              01000010         00010011         00000000          00000001


Message octet 7              00000010         00000000         00000000          00000001
Message octet 8              00000001         01000010         00010011          00000000


FCS octet 1                  xxxxxxxx         xxxxxxxx         xxxxxxxx          xxxxxxxx
FCS octet 2                  xxxxxxxx         xxxxxxxx         xxxxxxxx          xxxxxxxx
Flag                         01111110         01111110         01111110          01111110
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5.3.4                 On-Line Maintenance Functions
The packet-basedVoIP gateway is responsible for declaring alarms and status conditions. The packet-
basedVoIP gateway shall transmit alarm signals toward the network for detected failures, as described
below. The packet-basedVoIP gateway may also signal these failure conditions to the user via local
indicators. Also refer to ANSI T1.231 (Ref 14) for more information on alarm conditions and
performance monitoring.
5.3.4.1               Fault Conditions
5.3.4.1.1               Loss of Frame (LOF) (previously Out-of-Frame (OOF) Condition)
An out-of-frame condition shall be declared by the packet-basedVoIP gateway with the occurrence of a
particular density of framing bit errors (i.e., n or more errors out of m consecutive framing bits). Typical
values of n and m are 2 out of 4, 2 out of 5, and 3 out of 5. A LOF failure is declared when an out-of-
frame condition persists for a period of 2 to 10 seconds.
5.3.4.1.2               Loss of Signal (LOS)
An loss of signal defect is the occurrence of 175 ± 75 contiguous pulse positions with no pulses of either
positive or negative polarity at a DS1 line interface. A LOS failure shall be declared by the packet-
basedVoIP gateway when the LOS defect persists for a period 2 to 10 seconds.
5.3.4.1.3               Excessive Bipolar Violations (BPV)
An excessive bipolar violation condition shall be declared when any digital signal has BPVs in excess of
the threshold setting. The threshold setting for the BPV time shall be approximately 1000 seconds with a
BPV rate of 10-6 BPVs per bit.
5.3.4.1.4               Remote Alarm Indication (RAI)
A Remote Alarm Indication Signal (previously called the Yellow Alarm) is a trouble sectionalization
signal transmitted in the outgoing direction when a terminal determines that it has lost the incoming
signal. The packet-basedVoIP gateway shall transmit an RAI signal as defined below.
                                                                                                               Formatted: Highlight
The form of the RAI signal depends on the framing format in use. Facilities providing SF framing use an
inband RAI signal that consists of setting bit 2 in every channel to zero. Facilities providing ESF framing
use transmission of a repeating 16-bit pattern consisting of eight ones followed by eight zeros
(0000000011111111) continuously on the ESF data link for the duration of the alarm condition but not
for less than one second.
The following timing conventions should be applied in sending or receiving the RAI signal:
   (1)     The out-of-frame condition should persist for 2 to 3 seconds before sending the Yellow
           Alarm.
    (2)     The RAI should not be cleared unless the out-of-frame condition has cleared for more than 10
            to 20 seconds.
    (3)     Detection of the RAI should occur within 335 to 1000 milliseconds.
    (4)     The minimum time between the end of one transmission and the beginning of another
            transmission shall be one second. Certain services provided by the network may require
            longer time intervals than these minimum values, or may require equal "on" and "off"
            intervals, or both.
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5.3.4.1.5                Carrier Group Alarm
The Carrier Group Alarm function is defined as either being in the Red Alarm condition (packet-
basedVoIP gateway cannot frame on the received DS1 signal for 2 to 3 seconds) or receiving a RAI
(which indicates that the far endpoint cannot frame on the transmitted DS1 signal).
The packet-basedVoIP gateway should freeze its signaling state as soon as it loses frame synchronization
on its DS1 input. This should be done so that, for a 50% “ones” density, the probability of freezing an
incorrect signaling state should be less than 5%. If frame synchronization is not regained after the
nominal 2.5-second interval, the carrier group alarm state is entered. Once in this state, existing calls
should be dropped and no new calls allowed.
If frame synchronization is re-acquired for 10 to 20 seconds or an incoming RAI subsides for 100 to
1000 ms, the interface shall leave the carrier group alarm state.
5.3.4.1.6                 Alarm Indication Signal (AIS)
AIS is a trouble sectionalization signal transmitted in lieu of the normal signal to maintain transmission
continuity. It indicates to the receiving terminal that there is a transmission interruption located either at
the equipment originating the AIS signal or upstream of that equipment. When a valid signal is available,
the AIS may be removed. The AIS shall be generated as an unframed, all “ones” signal.
Either the packet-basedVoIP gateway or the far-end equipment may busy out an entire DS1 facility by
sending an AIS. If an AIS is received and since it is unframed, the Remote Alarm Indication signal shall
be transmitted to the far end.
                                                                                                                 Formatted: Indent: Hanging: 1.25", Outline
5.3.4.1.6.1          Trouble Sectionalization Signals                                                            numbered + Level: 7 + Numbering Style: 1, 2,
                                                                                                                 3, … + Start at: 1 + Alignment: Left + Aligned
The two signals: Alarm Indication Signal - Customer Installation (AIS-CI) and Remote Alarm Indication            at: 0.25" + Tab after: 1.25" + Indent at:
- Customer Installation (RAI-CI) are intended for use to differentiate whether a trouble exists within the       1.25"
network or within the packet-basedVoIP gateway .
Although the two signals may be applied independently, they are intended to be used together to locate
trouble in either direction of transmission to either side of the point of application of the signals.
From a public and private network perspective, AIS-CI and RAI-CI are detected by the carrier using
intermediate path monitoring either in a non-intrusive device or at a digital cross-connect system or other
DS1 line terminating equipment with intermediate path monitoring capability.
Since the following AIS-CI and RAI-CI are symmetric, and can be sent toward the packet-basedVoIP
gateway as well, the packet-basedVoIP gateway could also monitor these signals at the DS1 path
termination:
                                                                                                                 Formatted: Outline numbered + Level: 8 +
5.3.4.1.6.1.1        Alarm Indication Signal - Customer Installation (AIS-CI)                                    Numbering Style: 1, 2, 3, … + Start at: 1 +
                                                                                                                 Alignment: Left + Aligned at: 0" + Tab after:
AIS-CI is generated within the network and is transmitted toward the network, away from the packet-              1" + Indent at: 1", Tab stops: Not at 1"
basedVoIP gateway, when either an AIS defect or an LOS defect has been detected in the signal received
from the packet-basedVoIP gateway. This signal may transit the Network Interface from the network to
the packet-basedVoIP gateway as a result of far end action. The packet-basedVoIP gateway shall respond
to this signal only in as far as it is within the definition of AIS.
Generation of AIS-CI is optional. If provided, AIS-CI shall meet the requirements defined in T1.403-
1999, Annex D (Ref 2).
                                                                                                                 Formatted: Indent: Left: 0", Hanging: 1.56",
5.3.4.1.6.1.2             Remote Alarm Indication - Customer Installation (RAI-CI)                               Outline numbered + Level: 8 + Numbering
                                                                                                                 Style: 1, 2, 3, … + Start at: 1 + Alignment: Left
RAI-CI may be used to determine whether a problem that has been detected is in the network or in the             + Aligned at: 0" + Tab after: 1" + Indent at:
packet-basedVoIP gateway in the direction of transmission toward the packet-basedVoIP gateway. This              1", Tab stops: Not at 1"
signal may transit the Network Interface from the network to the packet-basedVoIP gateway as a result of
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far end action. The packet-basedVoIP gateway shall respond to this signal only in as far as it is within the
definition of RAI.
Generation of RAI-CI is optional. If provided, RAI-CI shall meet the requirements defined in T1.403-
1999, Annex D (Ref 2).
5.3.4.1.7                 Other Alarms
Other DS1 related alarm functions monitored by the packet-basedVoIP gateway include slip rate
detection which may be used for detecting loss of loop timing.
5.3.5                  Loopbacks
The packet-basedVoIP gateway shall provide a loopback function by automatic, manual, ESF data link,
inband or other4 means to assist in trouble isolation procedures. Line loopback is provided by looping the
receive line-pair to the transmit line-pair. ESF data link or inband signaling for control of loopbacks is
recommended. Inband signaling is the use of message channels to carry signaling information.
5.3.5.1                Inband Line Loopback Activation
The packet-basedVoIP gateway shall activate the loopback when it receives from the network a framed
pulse sequence consisting of a "1" followed by four "0's", repeated for at least 5 seconds. The frame
alignment bits overwrite the code pattern.
5.3.5.2                Inband Line Loopback Deactivation
The packet-basedVoIP gateway shall deactivate the loopback when it receives from the network a framed
pulse sequence consisting of a "1" followed by two "0's", repeated for at least 5 seconds. The frame
alignment bits overwrite the code pattern.5
5.3.5.3                Loopback Signals for the ESF
Signaling for loopback activation and deactivation by means of the ESF channel is controlled by bit-
oriented messages in the ESF data link. These messages are described in 5.3.3.4.1.
5.3.5.3.1                 ESF Loopback Activation Messages
Loopback activation messages shall not be returned to the Network Interface (e.g., by the requested
loopback)6. Accordingly, loopback activation shall be a two-step process as follows:

     (1)    The loopback activation message shall be sent at least 10 times, using a contiguous                       Formatted: Indent: Left: 0.25", Hanging:
            transmission as a preamble to a loopback activation request;                                              0.5", Numbered + Level: 1 + Numbering Style:
                                                                                                                      1, 2, 3, … + Start at: 1 + Alignment: Left +
                                                                                                                      Aligned at: 0.25" + Tab after: 0.5" + Indent
     (2)    The end of the transmission of the preamble specified in (1) shall constitute a request for               at: 0.5", Tab stops: Not at 0.5"
            loopback activation.
                                                                                                                      Formatted: Indent: Left: 0.25", Hanging:
5.3.5.3.2                  ESF Loopback Deactivation Messages                                                         0.5", Numbered + Level: 1 + Numbering Style:
                                                                                                                      1, 2, 3, … + Start at: 1 + Alignment: Left +
Deactivation messages shall be sent from a source transmitting in the same direction that the activation              Aligned at: 0.25" + Tab after: 0.5" + Indent
                                                                                                                      at: 0.5", Tab stops: Not at 0.5"
message was sent.




4.   This loopback may be provided by adjunct equipment such as NCTE.
5.   Embedded equipment exists which may be activated by the line loopback deactivate code and block the code
     from reaching the VoIP gateway, requiring manual intervention to deactivate the line loopback.
6.   Some embedded VoIP gateway equipment for ESF operation activates loopback immediately upon
     identification of the loopback activation message and does not delay actual loopback until either transmission
     of the loopback activation message ceases, or is replaced by the loopback retention message.
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Loopback deactivation may be accomplished in several ways. First, deactivation shall be initiated by the
use of the deactivate message specified for the purpose in Table 1. In addition, loopback deactivation
shall be initiated by any of the following:
                                                                                                                       Formatted: Indent: Left: 0.25", Hanging:
     (1)     The universal-loopback-deactivate message specified in Table 1.                                           0.5", Numbered + Level: 1 + Numbering Style:
                                                                                                                       1, 2, 3, … + Start at: 1 + Alignment: Left +
     (2)     AIS.                                                                                                      Aligned at: 0.19" + Tab after: 0.44" + Indent
     (3)     A data link signal consisting of two occurrences of a one-per-second performance message                  at: 0.44", Tab stops: Not at 0.44"

             separated by uninterrupted idle code.
These three methods of deactivation support the following:
                                                                                                                       Formatted: Indent: Left: 0.25", Hanging:
     (1)     A formal deactivation message for maintenance procedures.                                                 0.5", Numbered + Level: 1 + Numbering Style:
                                                                                                                       1, 2, 3, … + Start at: 1 + Alignment: Left +
     (2)     Prevention of simultaneously sustained loopbacks of any kind that face the same direction.                Aligned at: 0.19" + Tab after: 0.44" + Indent
     (3)     Deactivation of any inadvertent loopback by the presence of a normal signal containing all                at: 0.44", Tab stops: Not at 0.44"

             components of the ESF framing pattern.
     Note:   Equipment may also exist in a packet-basedVoIP gateway that does not respond to the
             "Universal Deactivate" message, AIS, or the PRM-and-idle-code combination. Loopbacks
             can be deactivated in such equipment by using the appropriate line or payload deactivate
             messages from Table 1.
5.3.5.3.3                  Loopback Retention
Many maintenance test signals are transmitted with framing. To permit these signals to be looped back,
the source of the framed test signal shall not generate any of the deactivation messages. One approach to
inhibiting the PRM-and-idle-code combination is to apply the priority message from Table 1, denoted as a
loopback retention message, for the duration of the maintenance activity. This message, when present in
the received signal, is another positive confirmation of the presence of a line loopback. In the case of a
payload loopback, the priority message does not appear in the returned signal.
5.3.5.4                 Packet-basedVoIP gateway Operation During Line Loopback
When line loopback is activated, the packet-basedVoIP gateway received data signals shall be transmitted
back to the network. The received data signal shall be regenerated by the packet-basedVoIP gateway
without change in framing format or removal of any bipolar violations. The line loopback shall also
operate upon the receipt of the patterns listed for inband line loopback (activation or deactivation) without
framing to accommodate embedded equipment that sends unframed (nonstandard) control signals.
5.3.5.5                 Packet-basedVoIP gateway Operation During Payload Loopback
When payload loopback is activated, the received information bits (192 information bits per frame) are
transmitted in the outgoing direction. The framing bits (frame synchronization, CRC, and DL) are
originated at the point of payload loopback. The payload loopback shall maintain bit-sequence integrity7
for the information bits; however, the payload loopback need not maintain the integrity of eight-bit time
slots, frames, or superframes. Payload loopback commands are described in 5.3.3.4.1.




7.   This requires that the timing of the transmitted payload loopback signal be synchronized with the timing of the
     received payload loopback signal.
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5.4         ISDN Primary Rate Access (DSS1) Requirements
5.4.1                 Introduction
The ISDN Primary Rate Access, as specified below, can be used as a trunk access to most local exchange
or inter-exchange carriers in the United States and in Canada. However at this time, some manufacturers'
implementations do not fully meet the standards listed below, therefore, to insure compatibility with a
given installation, specific Central Office Switch manufacturers' specifications should be checked for
deviations.
5.4.2                 Electrical and Physical Requirements
The electrical and physical requirements of the ISDN Primary Rate Access (U) Interface are specified in
ANSI T1.403.01-1999 (ISDN) Primary Rate Layer 1 Electrical Interface Specification (Ref 11).
5.4.3                 Data Link Layer Requirements
The Data Link (layer 2) requirements for the ISDN Primary Rate Access Interface are specified in ANSI
T1.602-1996 ISDN - Data-Link Signaling Specification for Application at the User-Network Interface
(Ref 12).
5.4.4                 Network Layer Requirements
The Network (Layer 3) requirements for the ISDN Primary Rate Access Interface Circuit Switched
Bearer Services are specified in ANSI T1.607-2000 Integrated Services Digital Network (ISDN) - Layer
3 Signaling Specification for Circuit-Switched Bearer Services for Digital Subscriber Signaling System
Number 1 (DSS1) (Ref 13).
                                                                                                             Formatted: Highlight
5.5         ISDN Private Network Signaling (PSS1 / QSIG) Requirements
5.5.1                 Introduction
                                                                                                             Formatted: Highlight
This section describes the requirements for 1544 kbps packet-based gateway-to-enterprise network
connectivity when two or more gateways are connected to form a private or enterprise network. The            Formatted: Highlight
gateways may be connected by using a dedicated point-to-point PRI, or through another interconnection        Formatted: Highlight
scenario.
                                                                                                             Formatted: Highlight
PSS1 is an ISO standard for Private Integrated Services Networks based on ITU-T Recommendation
Q931 - Digital subscriber signaling system No.1 - Network layer - ISDN user-network interface layer 3
specification for basic call control (Ref 25). The PSS1 Standards define the signaling protocol for          Formatted: Highlight
gateway-to-gateway signaling at the Q reference point. Hence, it is informally known as QSIG. ITU-T          Formatted: Highlight
Recommendation Q931 defines call control for applications such as packet-based gateway-to-network
                                                                                                             Formatted: Highlight
and is based on a master-slave or asymmetrical relation. QSIG, on the other hand, defines the call control
                                                                                                             Formatted: Highlight
signaling, as well as services, applicable to a peer-to-peer or symmetrical relation.
                                                                                                             Formatted: Highlight
The QSIG Protocol Model (Figure 13) is based on the ISO Reference Model. The Protocol Control entity
provides services to Call Control. Primitives exchanged across the boundary between Call Control and
Protocol Control correspond to the information flows exchanged between the Call Control functional
entities. Protocol Control provides the mapping between these primitives and messages transferred across
the inter-gateway link. In order to transfer messages, Protocol Control uses the services of the Data Link   Formatted: Not Strikethrough
Layer, which in turn uses the services of the Physical Layer. The actual Data Link Layer and Physical        Formatted: Highlight
Layer Protocols visible at the Q reference point are dependent on the gateway interconnection scenario,
                                                                                                             Formatted: Not Strikethrough
see ISO/IEC 11579-1:1994, Information Technology - Telecommunications and Information Exchange
                                                                                                             Formatted: Highlight
Between Systems - Part 1: Reference Configuration for PISN Exchanges (PINX), (Ref 22).
The generic functional protocol ISO/IEC 11582:1995, Information Technology - Telecommunications
and Information Exchange Between Systems - Private Integrated Services Network - Generic Functional
Protocol for the Support of Supplementary Services - Inter-exchange signaling procedures and protocol,
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(Ref 23) provides the means to exchange signaling information for the control of supplementary services
and Additional Network Features (ANFs) over a private or enterprise network. It does not, by itself,
control any supplementary service or ANF but rather provides generic services to specific Supplementary
Service Control entities. Procedures for individual supplementary services and ANFs based on these
generic procedures are defined in other standards or may be manufacturer-specific.
                                                                                                            Formatted: Highlight
The generic functional protocol operates at the Q reference point between two packet-based gateways in
conjunction with a Layer 3 protocol for basic call control ISO/IEC 11572:2000, Information Technology -
Telecommunications and Information Exchange Between Systems - Private Integrated Services Network
- Circuit Mode Bearer Services - Inter-exchange Signaling Procedures and Protocol, (Ref 24). Together,
these use the services of the Signaling Carriage Mechanism.
The generic functional protocol provides mechanisms for the support of supplementary services and
ANFs which relate to existing basic calls or services that are entirely independent of any existing basic
calls. In performing a supplementary service, whether call independent or call related, procedures in
ISO/IEC 11582 are applicable for information transfer procedures.
For the support of supplementary services and ANFs, both Basic Call Control, ISO/IEC 11572 and
Generic Functional Procedures 11582, are required in addition to compliance with the specific
supplementary service or ANF standard. ISO has developed an extensive series of standards for
supplementary services and ANFs. A complete list of these standards may be obtained from the ISO
online catalogue at http://www.iso.ch/.


              Signaling Layer                                         Signaling Layer


                   Call                                                     Call
                  Control                                                  Control


                                        Q                   Q
                  Protocol                                                Protocol
                  Control                                                 Control
                                            QSIG Protocol




                Signaling                                                Signaling
                 Carriage                   Data Link Layer               Carriage
                Mechanism                                                Mechanism

                                     PINX to PINX Connection




                                  Figure 13 - QSIG Protocol Model                                           Formatted: Highlight
                                                                                                            Formatted: Highlight
                                                                                                            Formatted: Normal, Tab stops: Not at 0.13"
5.5.2                 Test Plan for Multi-Vendor QSIG Interoperability Testing
                                                                                                            Formatted: Justified, Keep with next, Tab
                                                                                                            stops: Not at 0.13"
The test plan for multi-vendor QSIG interoperability testing is specified in TIA/EIA TSB123-2000, North
American Test Plan For Multi-Vendor QSIG Interoperability Testing (Ref 26). The document describes          Formatted: Highlight
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the test cases for the functional testing of QSIG features for the interoperability between at least two
vendors’ QSIG offerings. The tests described in the document are designed to be conducted within
private networks in point-to-point configurations that link the QSIG interfaces of the Private Integrated
Services Network Exchanges (PINXs) utilizing either BRI or PRI trunk interfaces. The scope of the test
plan includes the verification of the compatibility of QSIG basic call control procedures and the
functional compatibility of the following supplementary services defined in ISO/IEC standards:
            Calling and connected line identification;                                                     Formatted: Indent: First line: 0", Bulleted +
            Name identification;                                                                           Level: 1 + Aligned at: 0" + Tab after: 0.25" +
                                                                                                            Indent at: 0.25", Tab stops: 0.75", List tab +
            Call transfer (by join);                                                                       Not at 0.25"
            Call diversion;                                                                                Formatted: Bullets and Numbering
            Call offer;
            Call completion;
            Path replacement;
            Message waiting.
                                                                                                            Formatted: Justified, Keep with next, Tab
5.5.3                 Electrical and Physical Requirements                                                  stops: Not at 0.13"

No electrical and physical requirements are specified for the Private Integrated Services Network.
Specific requirements are dependent on the packet-based gateway interconnection scenario. See ISO/IEC       Formatted: Font: Not Italic
11579.                                                                                                      Formatted: Highlight

5.5.4                 Data Link Layer Requirements
No Data Link (Layer 2) requirements are specified by ISO for the Private Integrated Services Network.
Specific requirements are dependent on the packet-based gateway interconnection scenario, see ISO/IEC       Formatted: Font: Not Italic
11579.                                                                                                      Formatted: Highlight

5.5.5                 Network Layer Requirements
The Network (Layer 3) requirements for the Private Integrated Services Network are specified in ISO/IEC
11572 (Ref 24), ISO/IEC 11582 (Ref 23) and the various standards for supplementary services and ANFs.
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5.6          Channel-associated Signaling and Supervision Requirements
                                                                                                               Formatted: Heading 4
5.6.1                   General
                                                                                                               Formatted: Highlight
This section covers the basic channel-associated signaling requirements for packet-based gateway 1544
kbps interrface. The signaling protocol is compatible with the A, B, C, and D bit protocol associated with     Formatted: Highlight
the Extended Superframe Framing format (ESF).           These signaling protocols allow the far end to
terminate on a channel bank in the case of combination trunk or to terminate on a 1544 kbps interface
using the same protocol at a digital network node or another packet-based gateway. Subsection 5.6.2            Formatted: Font color: Red, Highlight
tabulates the ESF signaling protocols currently being proposed.                                                Formatted: Font color: Red

5.6.1.1                 Signaling Interface Types                                                              Formatted: Font color: Red, Highlight
                                                                                                               Formatted: Highlight
Table 4 lists the signaling trunk types and the equivalent channel units.
                                                                                                               Formatted: Highlight
                         Table 4 - Interface Type and Channel Unit Equivalent

             Interface Type                                    D-Bank Equivalent
                                        Packet-based Gateway End                      Far end
                Tie-Trunk                        4W E&M                           4W/2W E&M
            911-CAMA Trunk8                          DPO                               DPT
             CO/FX/WATS                             SAS/FXS                        SAO/FXO
                  DID                                DPT                               DPO
                  OPS                            SAO/FXO                            SAS/FXS

5.6.1.2                 Dial Pulse Address Signaling
Dial Pulse address signaling using A&B bits shall be supported.
5.6.1.3                 Trunk Signaling by Trunk Type
                                                                                                               Formatted: Highlight
The sequence of states for processing calls at the digital trunk interfaces is similar to that of the analog
trunk to allow combination trunk connection. In the tables, an X indicates that the received signaling bit
is not required for determining the signaling state and, depending on the terminating equipment, may be
an unreliable source of such information. Therefore, it should be ignored.
Where timing is required, the appropriate timing parameter for the analog trunk shall be used:
  (1)      Timing for ground start access lines is given in ANSI/TIA-464-C (Ref 1).                            Formatted: Highlight
                                                                                                               Formatted: Bullets and Numbering
      (2)    Timing for loop start access lines is given in ANSI/TIA-464-C (Ref 1).
                                                                                                               Formatted: Numbered + Level: 1 +
      (3)    Timing for DID is given in ANSI/TIA-464-C (Ref 1).                                                Numbering Style: 1, 2, 3, … + Start at: 1 +
      (4)    Timing for E&M tie trunks is given in ANSI/TIA-464-C (Ref 1).                                     Alignment: Left + Aligned at: 0.25" + Tab
                                                                                                               after: 0.75" + Indent at: 0.75"
      (5)    Timing for 911-CAMA is given in T1.411-1995 (Ref 11).                                             Formatted: Highlight
                                                                                                               Formatted: Highlight
                                                                                                               Formatted: Highlight
                                                                                                               Formatted: Numbered + Level: 1 +
                                                                                                               Numbering Style: 1, 2, 3, … + Start at: 1 +
                                                                                                               Alignment: Left + Aligned at: 0.25" + Tab
                                                                                                               after: 0.75" + Indent at: 0.75"



8     “911-CAMA” trunk in this section denotes the customer access to the Enhanced 911 Network, defined in
      ANSI T1.411-1994, (Ref 11).
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5.6.2                ESF Signaling Formats                                                                 Formatted: Highlight

The following tables present the ESF robbed-bit signaling protocols currently being formulated.
                                                                                                           Formatted: Highlight
5.6.2.1                 DID, Tie Trunk, and 911-CAMA Trunk Signaling
                                                                                                           Formatted: Bullets and Numbering


                    Transmit to Network                               Receive from Network
           State              A     B     C    D                   State               A    B     C    D
On-Hook                       0     0     0    0        On-Hook                        0    0     0    0

Off-Hook                      1     1     1    1        Off-Hook                       1    1     1    1


                                                                                                           Formatted: Highlight
5.6.2.2                 Loop Start Access Lines (including loop start FX/WATS Trunk)
                                                                                                           Formatted: Bullets and Numbering


                    Transmit to Network                               Receive from Network
           State              A     B     C    D                   State               A    B     C    D
Loop Opened                   0     1     0    1        Ringing                        0    0     0    0
Loop Closed                   1     1     1    1        Current Feed (not ringing)     0    1     0    1
                                                        Rev. Current Feed              0    1     0    0
                                                        Loop Opened                    1    1     1    1
                                                        (no current feed)


                                                                                                           Formatted: Highlight
5.6.2.3                 Ground Start Access Line (including ground start FX/WATS trunk)
                                                                                                           Formatted: Bullets and Numbering


                    Transmit to Network                               Receive from Network
           State              A     B     C    D                   State               A    B     C    D
Loop Opened                   0     1     0    1        Ringing                        0    0     0    0
Loop Closed                   1     1     1    1        Current Feed (not ringing)     0    1     0    1
Ring Ground                   0     0     0    0        Rev. Current Feed              0    1     0    0
(service request)
                                                        Loop Opened                    1    1     1    1
                                                        (no current feed)


                                                                                                           Formatted: Bullets and Numbering
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                                                                                                                 Formatted: Highlight
5.6.2.4                Off-Premises Station


                  Transmit to Network                                   Receive from Network
          State              A     B     C      D                   State                A      B     C     D
Ringing                      0     0      0     0       Loop Opened                       0     1     0      1

Not Ringing                  0     1      0     1       Loop Closed                       1     1     1      1


5.6.2.5                Private line auto ring                                                                    Formatted: Highlight

PLAR signaling states shall be defined below and are the same as those historically referred to as D4-type
PLAR1):


                  Transmit to Network                                   Receive from Network
          State              A     B     C      D                   State                A      B     C     D
Loop Opened (on-hook)        1     1      1     1       Loop Opened (on-hook) (2)         1     1     1      1

Loop Closed (off-hook)       0     0      0     0       Loop Closed (off-hook) (3)        0     0     0      0
Notes:
                                                                                                                 Formatted: Indent: Left: 0.25", Hanging:
    1.      These states are based on distant equipment that uses “D4” PLAR equipment. Some network              0.5", Numbered + Level: 1 + Numbering Style:
            equipment may exist that uses “D3” PLAR signaling states with opposite sense from “D4”               1, 2, 3, … + Start at: 1 + Alignment: Left +
            PLAR signaling; D3 PLAR signaling is not compatible with D4 PLAR signaling defined in                Aligned at: 0.75" + Tab after: 1" + Indent at:
                                                                                                                 1", Tab stops: Not at 1"
            this standard.
                                                                                                                 Formatted: Bullets and Numbering
    2.      When receiving A=1, B=1, C=1, D=1 signaling code, the packet-based gateway applies loop
                                                                                                                 Formatted: Font: Italic
            current feed to its station set.
                                                                                                                 Formatted: Font: Italic
    3.      When receiving A=0, B=0, C=0, D=0 signaling code, the packet-based gateway initially
            applies to the station set a 20 Hz alerting signal that is typically cadenced (e.g., 2 seconds on,
            4 seconds off).
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5.6.2.6               Ringdown                                                                              Formatted: Highlight

Ringdown signaling states shall be as defined below and are the same as those historically referred to as
Ringdown:


               Transmit to Network                                      Receive from Network
           State             A     B     C     D                     State            A     B     C     D
Idle (2)                     1     1     1     1          Idle (1)                    1     1     1     1

Ringing                      0     0     0     0          20 Hz tone                  0     0     0     0
Notes:
                                                                                                            Formatted: Font: Italic
    1.       During the idle state, the packet-based gateway typically applies a no-voltage (loop current
             feed open) condition toward the station set.                                                   Formatted: Indent: Left: 0.25", Hanging:
                                                                                                            0.5", Numbered + Level: 1 + Numbering Style:
    2.       During the idle state, the packet-based gateway equipment detects a no-tone condition from     1, 2, 3, … + Start at: 1 + Alignment: Left +
                                                                                                            Aligned at: 0.75" + Tab after: 1" + Indent at:
             the station set.                                                                               1", Tab stops: Not at 1"
                                                                                                            Formatted: Bullets and Numbering
                                                                                                            Formatted: Font: Italic
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6            TRANSMISSION REQUIREMENTS

6.1          General
The transmission requirements recommended in this standard for 1544 kbps packet-basedVoIP gateway
are specified in ANSI/TIA-912-A, IP Telephony Equipment, Voice Gateway Transmission Requirements
(Ref 18). It establishes performance and technical criteria for voice communications over Internet and
Local Area Networks interfacing and connecting with the various elements of public and private
telecommunications networks. Compliance with these requirements should assure quality service. It was
also developed in conjunction with ETSI TC STQ, who generated an equivalent half-channel loss plan
standard, ETSI ES 202 020, for voice gateways that is harmonized with this standard.
ANSI/TIA-912-A standard considers a voice gateway to be a device that performs voice routing functions
between:
   (1)    Telephones.
   (2)    Public and private networks.
   (3)    IP and Packet-based networks.
Voice gateways include, but are not limited to:
  (1)      Packet-based enterprise gateway equipment that is functionally equivalent to a TDM-based       Formatted: Highlight
           PBX.
  (2)      Voice over ADSL Integrated Access Device.
  (3)      Voice over Cable Multimedia Terminal Adaptor and Analog Terminal Adaptor.
The transmission requirements for packet-basedVoIP telephony equipment are intended to be coordinated
with the public network loss plan according to the principles of ANSI T1.508 (Ref 19) and to fully
comply with the regulatory requirements of ANSI/TIA-968-A and its associated addenda (Ref 6).
Voice quality-of-service issues such as the impact of transmission delay, speech compression and packet
loss are addressed in TIA/EIA/TSB32-A (Ref 20) and TIA/EIA/TSB116-A (Ref 21).                             Formatted: Highlight
                                                                                                          Formatted: Highlight
6.2          Echo Cancellation
                                                                                                          Formatted: Bullets and Numbering
      Echo Cancellation                                                                                   Formatted: Highlight

The packet-based gateway T1Voice gateway shall provide eEcho cancellation function to meet minimum        Formatted: Indent: Left: 0.25", Hanging:
                                                                                                          0.5", Tab stops: 0.75", List tab + Not at 0.5"
echo requirement in an end-to-end network connection to meet the following requirements.
                                                                                                          Formatted: Bullets and Numbering
      (1)    Echo cancellation ECAN function shall meet G.168 performance requirements specified in
                                                                                                          Formatted: Font color: Auto, Highlight
             ITU-T Recommendation G.168, Digital network echo cancellers (Ref 27).
                                                                                                          Formatted: Highlight
      (1)    Adopt network delay with eECAN function shall provide following Echo delay tail length s     Formatted: Bullets and Numbering
             of 8 ms to 128 msflexibility to allow for different PSTN network delay applications.
                                                                                                          Formatted: Highlight
      (2)                                                                                                 Formatted: Highlight
                                                                                                          Formatted: Highlight
                                                                                                          Formatted: Highlight
                                                                                                          Formatted: Bullets and Numbering
                                                                                                          Formatted: Numbered + Level: 1 +
                                                                                                          Numbering Style: 1, 2, 3, … + Start at: 1 +
                                                                                                          Alignment: Left + Aligned at: 0.25" + Tab
                                                                                                          after: 0.5" + Indent at: 0.5"
                                                                                                          Formatted: Bullets and Numbering
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                                                                                                           Formatted: Highlight
            minimum 24ms to 128ms delay
      (2)

7              DTMF SIGNALING REQUIREMENTS

7.1            General
This section provides requirements for address signaling using in-band Dual Tone Multifrequency
Signaling (DTMF) tones. Address signaling using dial pulsing (DP) may still find use in some legacy
switching equipment applications; however the mature state of DP technology and requirements make it
appropriate not to include in this standard. Dial pulse signaling requirements can be found in ANSI/TIA-
464-C Annex E (Ref 9).

7.1.1               Definition
Dual Tone Multifrequency (DTMF) address signaling is a method of signaling using the voice
transmission path. This method employs sixteen distinct signals, each composed of two voiceband            Formatted: Highlight
frequencies, one from each of two geometrically-spaced groups designated "low group" and "high group".
The selected spacing assures that no two frequencies of any group combination are harmonically related.

7.1.2               Criteria for DTMF Signal Processing
The following criteria are intended to ensure that DTMF signals received at and transmitted by the
packet-based gateway will provide reliable service in accomplishing the following functions:
      (1)      Process signaling through the voice transmission path from customer equipment to DTMF
               receivers in the packet-based gateways.
      (2)      Process signaling through the voice transmission path from the packet-based gateway to
               public network equipment DTMF receivers.
      (3)      Process address signaling through the voice transmission path from public and private       Formatted: Highlight

               network DTMF senders to DTMF receivers in the packet-based gateways.

7.1.3               Signaling Frequencies
DTMF signals shall consist of two sinusoidal tones, one from a high group of three frequencies and one
from a low group of four frequencies, which represent each of the characters shown below:

                                            Nominal High Group Frequencies (Hz)

                                     1209          1336            1477             1633

                         697          1              2               3                A
       Nominal
      Low Group          770          4              5               6                B
      Frequencies
         (Hz)            852          7              8               9                C
                         941          *              0               #                D
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7.2         DTMF Generator Characteristics
DTMF signals shall have the following characteristics when measured into a 600  resistive test
termination on the tip and ring conductors of a zero loss decoder at the network interface.                   Formatted: Highlight


7.2.1             Signal Levels
DTMF generators shall have the following steady state power levels:
      Per frequency, nominal                                                          -6 to -4 dBm
      Per frequency, minimum, low group                                                   -10 dBm
      Per frequency, minimum, high group                                                    -8 dBm
      Per frequency pair, maximum                                                           0 dBm
The maximum difference in power level between the frequency components of a frequency pair shall not
exceed 4 dB, and the level of the higher frequency must be 2±1 dB higher than the lower one
The maximum power in the frequency band below 3995 Hz delivered to a loop simulator shall not exceed
the following when averaged over 3-second interval:
      (1)   0 dBm when used for network control signaling.                                                    Formatted: Bullets and Numbering

      (2)   0 dBm when DTMF is used for manual entry end-to-end signaling. It shall not generate more
            than 40 DTMF digits per manual key stroke.

7.2.2             Frequency Deviation
The frequency components shall be within 1.5 percent of their nominal values in 7.1.3.

7.2.3             Pulsing Timing for DTMF Signals
Duration time of the elements of the DTMF signal cycle are defined as follows:
7.2.3.1                Rise Time
The time interval that begins when either frequency of the frequency pair exceeds -55 dBm and ends
when both frequencies of the pair exceed 90 percent of their respective steady-state amplitudes. Rise time
starts when the signal-off time ends.
7.2.3.2                Pulse Duration
The time interval that begins when the amplitude of the last frequency of the frequency pair exceeds 90
percent of that frequency's steady-state value and ends when either frequency amplitude falls below 90
percent of its respective steady state value. Pulse duration starts when the rise time ends.
7.2.3.3                Fall Time
The time interval that begins when the pulse duration ends and ends when both frequencies of the pair fall
below -55 dBm.
7.2.3.4                Signal-Off Time
The time interval that starts when the fall time ends and ends when the rise time of the next pulse starts.
7.2.3.5                Interdigital Interval
The sum of the fall time, signal-off time, and rise time. The interdigital interval starts when the pulse
duration ends.
7.2.3.6                Cycle Time
The sum of the pulse duration and the interdigital interval.
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Signal timing and sending rate for DTMF senders shall be as follows:

            Cycle time, minimum                                                 100 milliseconds
            Duration of two-frequency signal, minimum                            50 milliseconds
            Signal-off time, minimum                                             45 milliseconds
            Interdigital interval, maximum                                             3 seconds
            Rise Time, maximum                                                     5 milliseconds
The first digit shall be sent between 70 milliseconds and 5 seconds after reception of dial tone. Address
signaling shall never begin until the packet-based gateway has converted to the loop supervisory mode.

7.2.4             Voice Suppression
Voice energy from the station line or other source shall be suppressed by at least 45 dB relative to the
normal acoustic-to-electric transmit efficiency of the voice transmitter during DTMF signal transmission.
When senders are used, the suppression shall be maintained continuously until address signaling is
completed.

7.2.5             Extraneous Frequency Components
The total power of all extraneous frequencies in the voiceband above 500 Hz accompanying DTMF
signals shall be at least 16 dB below the level of each frequency component.

7.2.6             Tone Leak
In signal OFF intervals during transmission of address signals, no DTMF component shall leak onto the
transmission path at a level higher than -55 dBm.

7.2.7             Transient Voltage
Any transient voltage generated shall be constrained to occur within the first 5 ms after the end of the
signal-off interval and shall have an absolute peak magnitude not greater than 12 dB above the absolute
peak voltage of the ensuing steady-state DTMF pulse.

7.3         DTMF Receiver Characteristics

7.3.1             Signal Frequencies
                                                                                                              Formatted: Highlight
DTMF receivers shall provide reliable reception of the frequency-pair signals for the Sixteen characters
given in 7.1.3.

7.3.2             Frequency Deviation
The receiver shall register the frequency-pair signals when both frequencies fall within 1.5% of their
nominal values; the receiver shall not register a signal when either frequency deviates more than 3.5%
from its nominal value.

7.3.3             Registration Time
The receiver shall register DTMF signals as short as 40 ms, shall recognize interdigital intervals as short
as 40 ms, and shall reject DTMF signals with a duration less than 23 ms. The receiver shall register
DTMF signals having cycle times (tone ON plus tone OFF interval) of 93 ms or greater.

7.3.4             Recognition Level
Receivers shall register DTMF signals having a power per frequency of -25 to 0 dBm and with the high-
frequency tone power +4 to -8 dB relative to that of the low-frequency tone.
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7.3.5             Registration in the Presence of Dial Tone
Receivers shall register DTMF signals in the presence of precise dial tone. Precise dial tone from packet-
based gateways is the combination of 350 and 440 Hz (2.0 percent) at a level of -16 dBm (±3.0 dB) per
frequency at the input to the receiver. These frequency and level tolerances are wider than specifications
for dial tone supplies (section 8, Table 5) but precise dial tone supplies currently in the field may have   Formatted: Highlight
deviations as wide as those given.
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8           CALL PROGRESS SIGNALING
Call progress signals (tones) are audible signals provided toward a caller during the process of setting up,
holding, or transferring a call. This standard applies to call progress signals heard by the following types
of callers:
      (1)   Callers located in the public switched telephone network (PSTN).
      (2)   Callers located in other packet-based gateways or other switching systems accessing this
            packet-based gateway via tie trunks or other facilities.
Call progress signals consist of single-frequency and dual-frequency combinations of sinusoidal voltages
applied in specific cadences and in accordance with specific ON-OFF patterns. This standard essentially
follows the telephone industry Precise Tone Plan.
The objective of this standard is to encourage and promote the uniform adoption throughout the industry
of the call progress signals herein defined to minimize user confusion that can result when a number of
different manufacturers' packet-based gateways are in use in any given association.


                        Standard Signals                            Other Signals

             Dial                                      Recall Dial
             Reorder                                   Special Audible Ring
             Busy                                      Line Lockout Warning
             Audible Ring                              Intercept
                                                       Call Waiting
                                                       Busy Verification
                                                       Executive Override
                                                       Confirmation
                                                       Stutter Dial
The objective of this standard is to encourage and promote the uniform adoption throughout the industry
of the call progress signals herein defined to minimize user confusion that can result when a number of
different manufacturers' gateways are in use in any given association.                                         Formatted: Highlight


8.1         Call Progress Signals Sent to the VoIP networks
The four signals that find most frequent use in the VoIP networks are Dial, Reorder, Busy, and Audible
Ring. These four signals are classified "standard" for convenience and are listed in Table 5. Although
other signals can also be sent through the VoIP networks, this standard requires conformity only to the
four "standard" signals. This minimizes user confusion, reoriginations, and errors in performance indices
relating to percent failure of call completion due to busy conditions and various equipment failures.
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                             Table 5 - Standard Call Progress Signals                                        Formatted: Space Before: 3 pt



                                Permissible Power Level Per
                                        Frequency                  Frequency
                                                                                      Interruption
  Name        Frequency                                                to
                                Desirable        Mandatory                              Pattern
                                                                   Frequency
                             Max.      Min.      Max.     Min.      Balance
                 (Hz)       (dBm)     (dBm)     (dBm)     (dBm)       (dB)
Dial          350 + 440       -16      -17.5      -16      -26          3       No Interruption Pattern
Tone                                                                            (Steady Tone)

Reorder       480 + 620      -19.5     -22.5     -19.5     -35          3       Repetition of tone ON
Tone                                                                            for 0.25 ± 0.025 s, and
                                                                                tone OFF for 0.25 ±
                                                                                0.025 s.
Busy          480 + 620      -19.5     -22.5     -19.5     -35          3       Repetition of tone ON
Tone                                                                            for 0.5 ± 0.05 s, and tone
                                                                                OFF for 0.5 ± 0.05 s.
Audible       440 + 480      -14.5     -17.5     -14.5     -30          3       Repetition of tone ON
Ring                                                                            for 0.8 to 1.2 s and tone
Tone                                                                            OFF for 2.7 to 3.3 s. or
                                                                                tone ON for 1.8 to 2.2 s
                                                                                and tone OFF for 3.6 to
                                                                                4.4 s

Note:
All power values shall be as measured into a 600  load at the VoIP analog telephone port. The signal
power limitation requirements in ANSI/TIA-968-A (Ref 7) not applicable to on-premises customer
equipment may be more restrictive than the permissible power limits given in this table.
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                                    Table 6 - Other Call Progress Signals

                                Permissible Power Level Per
                                    Frequency (Note 1)               Frequency
                                                                                         Interruption
   Name        Frequency                                                 to
                                Desirable           Mandatory                              Pattern
                                                                     Frequency
                             Max.        Min.      Max.     Min.      Balance

                  (Hz)      (dBm)       (dBm)     (dBm)    (dBm)        (dB)
Recall          350 + 440     -16        -17.5      -16      -26            3    Three bursts of tone ON for
Dial                                                                             0.08 to 0.12s, and tone OFF
Tone                                                                             for 0.08 to 0.12s, followed by
                                                                                 dial tone.
Special         440 + 480    -14.5       -17.5     -14.5     -30            3    Repetition of combined tones
Audible                                                                          ON for 0.8 to 1.2s, followed
Ring                                                                             by 440 Hz tone ON for 0.2s,
Tone                                                                             and tone OFF for 2.7 to 3.3s.
Intercept       440 + 620    -12.5       -15.5     -12.5     -33        N/A      Repetition of alternating the
Tone                                                                             two frequencies, each ON for
                                                                                 0.16 to 0.30s, with a total
                                                                                 cycle duration of 0.5 ± 0.05s.
Call              440        -12.5       -15.5     -12.5     -33        N/A      One application, for 0.1 to
Waiting                                                                          0.3s, followed by a second
Tone                                                                             application about 10 seconds
                                                                                 later (Note 3)
Line Lockout    (Note 2)         (Note 2)             (Note 2)          N/A      Tone ON for approximately
Warning                                                                          10s once.
Tone
Busy              440        -12.5       -15.5     -12.5     -33        N/A      One burst of tone ON for 1.5
Verification                                                                     to 2.0 s, (Note 4) before
Tone                                                                             attendant intrudes, followed
                                                                                 by bursts of tone ON for 0.5 to
                                                                                 0.8s, 8 to 10s apart for as long
                                                                                 as the interruption lasts.
Executive         440        -12.5       -15.5     -12.5     -33        N/A      One burst of tone ON for 2.0
Override                                                                         to 4.0 s, (Note 4) before
Tone                                                                             overriding station intrudes.
Confirmation    350 + 440     -16        -17.5      -16      -26            3    Three bursts of tone ON for
Tone                                                                             0.08 to 0.12s, 0.08 to 0.12s
                                                                                 apart.
Stutter         350 + 440     -16        -17.5      -16      -26            3    Repetition of tone ON for 0.09
Dial Tone                                                                        to 0.16s, and tone OFF for
                                                                                 0.09 to 0.16s for a period of
                                                                                 about    2s,    followed    by
                                                                                 continuous dial tone.
  Note:
  All power values shall be as measured into a 600  load at the VoIP analog telephone port. The signal
  power limitation requirements in ANSI/TIA-968-A (Ref 7) not applicable to on-premises customer
  equipment may be more restrictive than the permissible power limits given in this table.
  Notes on Table 5 and Table 6:
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   1.      All power values shall be as measured into a 600  load at the VoIP analog telephone port.
   2.      Line Lockout Warning Tone is no longer recommended; however, when it is required either
           Intercept Tone, Reorder Tone, or Busy Tone may be used.
   3.      The application of Call Waiting tone may be a single tone burst or multiple tone bursts, e.g., to
           permit the called user to tell the difference between externally-originated and internally-
           originated calls. The application should be twice, once when the incoming call arrives, and
           then again approximately 10 seconds later if the call-waiting line (the called user) has not yet
           responded.
   4.      The difference in duration between Busy Verification and Executive Override Tones is
           intended to be sufficient to permit ready distinction between the tones.
   5.      Stutter Dial Tone is used as an indication to the user, e.g., message waiting. In message
           waiting applications, Stutter Dial Tone is also known as Message Waiting Dial Tone.
   6.      Studies have shown that the lower level tones that are transmitted over trunks should be 6 dB
           hotter at the trunk interface (than at the line interface) to compensate for increased loss on the
           end-to-end connection. In the case of tones used at higher levels, the 6 dB difference is not
           used since power at trunk interfaces must be limited to -13 dBm0 total when averaged over
           any three-second interval to prevent carrier overload. Maximum permissible powers listed
           are consistent with this requirement taking into account the allowable interruption rates for
           the various tones. Uninterrupted tones, such as Dial Tone and Intercept Tone, shall be
           continuously limited to -13 dBm.

8.2         Definitions of Call Progress Signals

8.2.1                    Standard Signals
8.2.1.1                  Dial Tone
                                                                                                                 Formatted: Highlight
Dial tone is applied toward a caller as an indication that the packet-based gateway is ready to receive
address signals. Dial tone shall be removed immediately upon recognition of the first keyed address
signal, or upon permanent timeout.
8.2.1.2                  Reorder Tone
Reorder tone is variously referred to as paths-busy tone and fast-busy tone. This signal is applied toward
the caller when call blockage is encountered due to unavailability of equipment or channels. This signal
shall be held applied as long as the caller remains off-hook. On calls originated by a local packet-based        Formatted: Highlight
gateway caller, in some instances, a packet-based gateway may disconnect the signal approximately 30
seconds after the caller has been connected to Reorder tone. On incoming calls from the public network
or other switching systems, the packet-based gateway shall not disconnect the signal until it receives a
disconnect indication from the caller.
8.2.1.3                  Busy Tone
Busy tone, sometimes referred to as slow-busy tone, is applied toward the caller as an indication that the
called station line or all lines in a called line hunting group are busy. This signal is normally held applied
as long as the caller remains off-hook. In some instances on calls originated by a local packet-based
gateway caller, a packet-based gateway may disconnect the signal approximately 30 seconds after the
caller has been connected to busy tone. On incoming calls from the public network or other switching
systems, the packet-based gateway shall not disconnect the signal until it receives a disconnect indication
from the caller.
8.2.1.4                  Audible Ring Tone
Audible ring tone, sometimes referred to as ringback tone, is applied toward the caller as an indication
that the called station, an attendant, or other destination is being or has been alerted. This signal shall be
held applied as long as the caller remains off-hook and shall be removed when the called station,
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attendant, or other destination answers. If the called party does not answer, audible ring tone shall be held
applied until the caller hangs up.

8.2.2              Other Signals
8.2.2.1                  Recall Dial Tone
Recall Dial tone is applied toward a packet-based gateway caller who is on an established connection and
has signaled, by hookswitch flash or other means, that the keying or dialing of additional digits is desired.
Recall Dial tone shall be removed immediately upon recognition of the first keyed address signal,
immediately upon recognition of the first rotary dial pulse or upon permanent timeout.
8.2.2.2                  Special Audible Ring Tone
Special Audible Ring tone is transmitted to the calling packet-based gateway party to indicate that the
called line or location has the Call Waiting feature and is being alerted. The Special Audible Ring Signal
is intended to sound like regular Audible Ring for the untrained user, yet provide a distinctive signal for
the knowledgeable user.
8.2.2.3                  Line Lockout Warning Tone
Line Lockout Warning tone is applied to a packet-based gateway station line if the line is off-hook but
fails to complete dialing within a specified interval or if the line fails to disconnect at the conclusion of a
call. A unique tone signal is no longer required. Intercept, Reorder Tone, or Busy Tone may be applied
for approximately ten seconds after the line has been placed in lockout. Intercept Tone or Busy Tone
shall never be returned over trunks as a Line Lockout Warning indication. Trunks shall be given Reorder
tone.
8.2.2.4                   Intercept Tone
The packet-based gateway should have means to provide an indication to the packet-based gateway
station user that the call has been blocked by the packet-based gateway. Intercept tone may be used for
this purpose; however, the use of intercept tone will not effectively provide the packet-based gateway user
with information for reporting call blockage. This signal shall be removed when the calling party
disconnects (see 5.1.3.5 for DID intercept treatment).
8.2.2.5                  Call Waiting Tone
Call Waiting tone is applied to a busy packet-based gateway to indicate to the station user that a call is
waiting. It consists of a single tone burst or multiple tone bursts, e.g., to permit the called user to tell the
difference between externally-originated and internally-originated calls. The application of the burst or
multiple bursts should be twice, once when the incoming call arrives, and then again approximately 10
seconds later if the call-waiting line (the called user) has not yet responded. The tone shall be heard only
by the party being called.
8.2.2.6                  Busy Verification Tone
Busy Verification tone is a burst of tone applied to a connection to indicate to all members of the
connection that an attendant is about to enter the connection. Intermittent signal burst shall continue to be
applied to the connection as long as the attendant remains connected.
8.2.2.7                  Executive Override Tone
Executive Override tone is a burst of tone applied to a connection to indicate to all members of the
connection that an overriding party will be bridged onto the connection.
8.2.2.8                  Confirmation Tone
Confirmation tone consists of bursts of tone applied toward a packet-based gateway to indicate that a
feature has been successfully activated or deactivated.
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8.2.2.9                 Stutter Dial Tone
Stutter dial tone is applied toward a caller as an indication that the packet-based gateway is ready to
receive address signals and to indicate another condition, e.g., message waiting. Stutter dial tone shall be
removed immediately upon recognition of the first rotary dial pulse, or upon permanent timeout.

8.3         Electrical Standards for Call Progress Signals

8.3.1             Industry Standard Precise Tone Plan
Dial, Reorder, Busy, and Audible Ring signals consist of standard tones that comply with the industry
standard precise tone plan. This tone plan is based on the use of four pure tones assigned either singly or
in pairs (not modulated). These tones are applied continuously and at a variety of cadences. The
frequencies, their levels, and their cadences shall be as described in Table 6.

8.3.2             Other Call Progress Signals
                                                                                                               Formatted: Highlight
Packet-based gateways should provide other call progress signals in accordance with Table 6. However,
it is recognized that some Packet-based gateways will not comply with Table 6.                                 Formatted: Highlight
                                                                                                               Formatted: Highlight
 This is not a T1 parameter , this is for analog interface??

8.3.3             Frequency Tolerance
Frequency tolerance shall be ± 0.5% per frequency.

 This is not a T1 parameter , this is for analog interface??

7.          DTMF GENERATOR and RECEIVER CHARACTERISTICS

7.1         General
This section provides receiver requirements for address signaling using in-band Dual Tone
Multifrequency Signaling (DTMF) tones. Address signaling using dial pulsing (DP) may still find use in
some legacy switching equipment applications; however the mature state of DP technology and
requirements make it appropriate not to include in this standard. Dial pulse signaling requirements can be
found in ANSI/TIA-464-C Annex E (Ref 9).

7.1.1             Definition
Dual Tone Multifrequency (DTMF) address signaling is a method of signaling using the voice
transmission path. This method employs twelve distinct signals, each composed of two voiceband
frequencies, one from each of two geometrically-spaced groups designated "low group" and "high group".
The selected spacing assures that no two frequencies of any group combination are harmonically related.
A fourth high-group frequency (1633 Hz) used in certain special applications is not covered in this
standard.

7.1.2             Criteria for DTMF Signal Processing
The following criteria are intended to ensure that DTMF signals received at and transmitted by the VoIP
gateway will provide reliable service in accomplishing the following functions:
      (1)   Process signaling through the voice transmission path from customer equipment to DTMF
            receivers in the VoIP gateways.
      (2)   Process signaling through the voice transmission path from the VoIP gateway to public
            network equipment DTMF receivers.
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      (3)    Process address signaling through the voice transmission path from public network DTMF
             senders to DTMF receivers in the VoIP gateways.

7.1.3               Signaling Frequencies
DTMF signals shall consist of two sinusoidal tones, one from a high group of three frequencies and one
from a low group of four frequencies, which represent each of the characters shown below:

                                                  Nominal High Group Frequencies (Hz)

                                                1209                  1336               1477

                               697                1                    2                  3
       Nominal
      Low Group                770                4                    5                  6
      Frequencies
         (Hz)                  852                7                    8                  9
                               941                *                    0                  #



7.2          DTMF Generator Characteristics
DTMF signals shall have the following characteristics when measured into a 600  resistive test
termination on the tip and ring conductors at the network interface.

7.2.1               Signal Levels
DTMF generators shall have the following steady state power levels:
      Per frequency, nominal                                                       -6 to -4 dBm
      Per frequency, minimum, low group                                                  -10 dBm
      Per frequency, minimum, high group                                                  -8 dBm
      Per frequency pair, maximum                                                          0 dBm
The maximum difference in power level between the frequency components of a frequency pair shall not
exceed 4 dB, and the level of the higher frequency must be 2±1 dB higher than the lower one
The maximum power in the frequency band below 3995 Hz delivered to a loop simulator shall not exceed
the following when averaged over 3-second interval:
      (1)0 dBm when used for network control signaling.                                                      Formatted: Bullets and Numbering

      (2)    0 dBm when DTMF is used for manual entry end-to-end signaling. It shall not generate more
             than 40 DTMF digits per manual key stroke.

7.2.2               Frequency Deviation
The frequency components shall be within 1.5 percent of their nominal values in 7.1.3.

7.2.3               Pulsing Timing for DTMF Signals
Duration time of the elements of the DTMF signal cycle are defined as follows:
7.2.3.1                Rise Time
The time interval that begins when either frequency of the frequency pair exceeds -55 dBm and ends
when both frequencies of the pair exceed 90 percent of their respective steady-state amplitudes. Rise time
starts when the signal-off time ends.
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7.2.3.2                Pulse Duration
The time interval that begins when the amplitude of the last frequency of the frequency pair exceeds 90
percent of that frequency's steady-state value and ends when either frequency amplitude falls below 90
percent of its respective steady state value. Pulse duration starts when the rise time ends.
7.2.3.3                Fall Time
The time interval that begins when the pulse duration ends and ends when both frequencies of the pair fall
below -55 dBm.
7.2.3.4                Signal-Off Time
The time interval that starts when the fall time ends and ends when the rise time of the next pulse starts.
7.2.3.5                Interdigital Interval
The sum of the fall time, signal-off time, and rise time. The interdigital interval starts when the pulse
duration ends.
7.2.3.6                Cycle Time
The sum of the pulse duration and the interdigital interval.


Signal timing and sending rate for DTMF senders shall be as follows:

            Cycle time, minimum                                                   100 milliseconds
            Duration of two-frequency signal, minimum                               50 milliseconds
            Signal-off time, minimum                                                45 milliseconds
            Interdigital interval, maximum                                                3 seconds
            Rise Time, maximum                                                       5 milliseconds
The first digit shall be sent between 70 milliseconds and 5 seconds after reception of dial tone. With
ground start operation, the network tip ground alone shall not be used as an indication to start DTMF
sending. In ground start operation with network switches in which dial tone and tip ground appear
simultaneously, or dial tone and battery and ground appear simultaneously, the first digit shall be sent
between 70 milliseconds and 5 seconds after the tip conductor is grounded. In any case, address signaling
shall never begin until the VoIP gateway has converted to the loop supervisory mode.

7.2.4              Voice Suppression
Voice energy from the station line or other source shall be suppressed by at least 45 dB relative to the
normal acoustic-to-electric transmit efficiency of the voice transmitter during DTMF signal transmission.
When senders are used, the suppression shall be maintained continuously until address signaling is
completed.

7.2.5              Extraneous Frequency Components
The total power of all extraneous frequencies in the voiceband above 500 Hz accompanying DTMF
signals shall be at least 16 dB below the level of each frequency component.

7.2.6              Tone Leak
In signal OFF intervals during transmission of address signals, no DTMF component shall leak onto the
transmission path at a level higher than -55 dBm.
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7.2.7             Transient Voltage
Any transient voltage generated shall be constrained to occur within the first 5 ms after the end of the
signal-off interval and shall have an absolute peak magnitude not greater than 12 dB above the absolute
peak voltage of the ensuing steady-state DTMF pulse.

7.3         DTMF Receiver Characteristics

7.3.1             Signal Frequencies
DTMF receivers shall provide reliable reception of the frequency-pair signals for the twelve characters
given in 6.1.3.

7.3.2             Frequency Deviation
The receiver shall register the frequency-pair signals when both frequencies fall within 1.5% of their
nominal values; the receiver shall not register a signal when either frequency deviates more than 3.5%
from its nominal value.

7.3.3             Registration Time
The receiver shall register DTMF signals as short as 40 ms, shall recognize interdigital intervals as short
as 40 ms, and shall reject DTMF signals with a duration less than 23 ms. The receiver shall register
DTMF signals having cycle times (tone ON plus tone OFF interval) of 93 ms or greater.

7.3.4             Recognition Level
Receivers shall register DTMF signals having a power per frequency of -25 to 0 dBm and with the high-
frequency tone power +4 to -8 dB relative to that of the low-frequency tone.

7.3.5             Registration in the Presence of Dial Tone
Receivers shall register DTMF signals in the presence of precise dial tone. Precise dial tone from VoIP
gateways is the combination of 350 and 440 Hz (2.0 percent) at a level of -16 dBm (±3.0 dB) per
frequency at the input to the receiver. These frequency and level tolerances are wider than specifications
for new dial tone supplies (8.3, Table 4) but precise dial tone supplies currently in the field may have
deviations as wide as those given.

8           CALL PROGRESS SIGNALING
Call progress signals (tones) are audible signals provided toward a caller during the process of setting up,
holding, or transferring a call. This standard applies to call progress signals heard by the following types
of callers:
      (1)   Callers located in the public switched telephone network (PSTN).
      (2)   Callers located in other VoIP gateways or other switching systems accessing this VoIP
            gateway via tie trunks or other facilities.
Call progress signals consist of single-frequency and dual-frequency combinations of sinusoidal voltages
applied in specific cadences and in accordance with specific ON-OFF patterns. This standard essentially
follows the telephone industry Precise Tone Plan.
The objective of this standard is to encourage and promote the uniform adoption throughout the industry
of the call progress signals herein defined to minimize user confusion that can result when a number of
different manufacturers' VoIP gateways are in use in any given association.
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8.1         Call Progress Signals Sent to the PSTN
The four signals that find most frequent use in VoIP gateways are Dial, Reorder, Busy, and Audible Ring.
These four signals are classified "standard" for convenience and are listed in Table 4. This standard
requires conformity only to the four "standard" signals. This minimizes user confusion, reoriginations,
and errors in central office switching system performance indices relating to percent failure of call
completion due to trunk busy conditions and various equipment failures.

8.2         Definitions of Standard Call Progress Signals

8.2.1              Dial Tone
Dial tone is applied toward a caller as an indication that the VoIP gateway is ready to receive address
signals. Dial tone shall be removed immediately upon recognition of the first keyed address signal or
immediately upon recognition of the first rotary dial pulse, or upon permanent timeout.

8.2.2              Reorder Tone
Reorder tone is variously referred to as paths-busy tone, all-trunks-busy tone and fast-busy tone. This
signal is applied toward the caller when call blockage is encountered due to unavailability of equipment
or channels. This signal shall be held applied as long as the caller remains off-hook. On incoming calls
from the public network or other switching systems, the VoIP gateway shall not disconnect the signal
until it receives a disconnect indication from the caller.

8.2.3              Busy Tone
Busy tone, sometimes referred to as slow-busy tone, is applied toward the caller as an indication that the
called station line or all lines in a called line hunting group are busy. This signal is normally held applied
as long as the caller remains off-hook. On incoming calls from the public network or other switching
systems, the VoIP gateway shall not disconnect the signal until it receives a disconnect indication from
the caller.

8.2.4              Audible Ring Tone
Audible Ring tone, sometimes referred to as ringback tone, is applied toward the caller as an indication
that the called station, an attendant, or other destination is being or has been alerted. This signal shall be
held applied as long as the caller remains off-hook and shall be removed when the called station,
attendant, or other destination answers. If the called party does not answer, Audible Ring tone shall be
held applied until the caller hangs up.

8.3         Electrical Standards for Call Progress Signals

8.3.1              Industry Standard Precise Tone Plan
Dial, Reorder, Busy, and Audible Ring signals consist of standard tones that comply with the industry
standard precise tone plan. This tone plan is based on the use of four pure tones assigned either singly or
in pairs (not modulated). These tones are applied continuously and at a variety of cadences. The
frequencies, their levels, and their cadences shall be as described in Table 4.

8.3.2              Frequency Tolerance
Frequency tolerance shall be ± 0.5% per frequency.

8.3.3              Tone Levels
At the trunk interface, noise and distortion products from the generation of call progress tones shall be at
least 40 dB below the total power of the fundamental tone levels.
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                      Table 4 - Standard Call Progress Signals

                      Permissible Power Level
                          Per Frequency                          Interruption
   Name   Frequency
                                                                    Pattern
                         Max.         Min.
            (Hz)        (dBm)         (dBm)
Dial      350 + 440       -16         -17.5     No Interruption Pattern (Steady Tone)
Tone
Reorder   480 + 620      -19.5        -22.5     Repetition of tone ON for 0.25 ± 0.025 s,
Tone                                            and tone OFF for 0.25 ± 0.025 s.
Busy      480 + 620      -19.5        -22.5     Repetition of tone ON for 0.5 ± 0.05s, and
Tone                                            tone OFF for 0.5 ± 0.05 s.
Audible   440 + 480      -14.5        -17.5     Repetition of tone ON for 0.8 to 1.2 s and
Ring                                            tone OFF for 2.7 to 3.3 s. or tone ON for
Tone                                            1.8 to 2.2 s and tone OFF for 3.6 to 4.4 s
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                                  Annex A.     Bibliography
                                This annex is informative only
                                and is not part of this standard.


   TIA Engineering Style Manual of January 30, 1992                                              Formatted: Indent: Hanging: 0.5", Bulleted +
                                                                                                  Level: 1 + Aligned at: 0.25" + Tab after: 0.5"
   IEEE Standard 100-1996, IEEE Standard Dictionary of Electrical and Electronic Terms           + Indent at: 0.5"

   ANSI T1.523-2001: “Telecom Glossary 2000”
   ETSI EN 300 011 – 1 v1.2.2 (2000-05): “Integrated Service Digital Network (ISDN); Primary
    Rate User Network Interface (UNI); Part 1: layer 1 Specification”.
   ITU-T Recommendation G.810 (08/96): “Definitions and terminology for synchronization
    networks”
   Telcordia Technical Advisory TA-NPL-000436, Digital Network Synchronization Plan

								
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