IN in Mobile Services
Manish Das
What is the Intelligent Network (IN)?
• ‘Intelligence’ of an ‘Intelligent Network’ lies in its capability of
providing personalized services to the users.
• This has been achieved by separating service logic and service
data from the switch to which the end user belongs.
• Introduce value added services over a large network at much
reduced cost, complexity and time on top of existing infrastructure.
From To
Call Processing Logic
Service Logic
SSP
SS7 SCP Service Logic
Call Processing Logic
• Call processing software and service related software in each SPC Switch. • Software interacts to complete calls and invoke services.
• Call processing software in Service Switching Point (SSP). • Service Logic in SCP. • SSP dialogs with SCP to determine how to process call.
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Manish Das
Basic components of IN
SCP SMF SCE IP SSP CCSN STP Service Control Point Service Management Function Service Creation Environment Intelligent Peripheral Service Switching Point Common Channel Signaling Network Signal Transfer Point
SCE
SMF
SCP
CCSN
IP
STP
STP
LEC/CLEC Network
SSP SSP SSP SSP
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STP
SSP
SSP
A GSM Network
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Requirements of Mobile Networks
• Real time charging of Voice, SMS and Data calls. • Providing operator specific services seamlessly even when roaming in other networks. • Charging real time for all services while roaming.
So, CAMEL aims to provide services irrespective of user’s location Transparent to subscriber CAMEL-based services “Switch”-based services “HLR”-based services Seamless services Home Roaming
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IN in Mobile Network
• Mobile networks are Intelligent Network structured networks, they have centralized databases (in GSM HLR, VLR) which correspond to IN SCP. GSM also supplies many of the supplementary services that can be supported on fixed networks by IN solutions. • IN in Mobile networks is a subset of Landline IN, but customized to meet the special requirements of Mobile services, hence named Customized Application for Mobile Enhanced Logic (CAMEL). • Mobile services has some unique features like handover, location update, roaming etc.
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Manish Das
Components in IN
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Some useful concepts
• Points in call (PIC) The points during the call when the IN service logic is allowed to interact with the basic call processings are identified as Points in Call (PICs). So PICs are the activities in MSC/VLR associated with call processing like, Collection of digits, routing, alerting etc. PICs are vendor independent, providing a standardized view of call processing behaviour. Detection Points (DP) The points in call processing or during a call, where transfer of control IN service logic or notification of service logic take place. DPs are placed between PICs. DPs can be of two typesNotification (DP-N) and Response (DPR).
PIC DP PIC
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IN Triggers
• Call termination triggers – Called party busy – No answer • Call origination triggers – Calling party – Dialed number • Trigger categories – Subscribed (individual subscriber-based) – Office/group
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OSI Reference model and Signaling in CAMEL
CAP
Application Presentation Session Transport Network Data link Physical
TCAP
ISUP
NULL
User / Application Parts
SCCP MTP Level 3 MTP Level 2 MTP Level 1
Network Part
OSI-RM
SS7
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Manish Das
CAMEL Subscription Information
• • • Originating CAMEL Subscription Information (O-CSI): The O-CSI identifies the subscriber as having originating CAMEL services. Terminating CAMEL Subscription Information (T-CSI): The T-CSI identifies the subscriber as having terminating CAMEL services. Supplementary Service Notification CAMEL Subscription Information (SS-CSI): The SS-CSI identifies the subscriber as having supplementary service invocation notification CAMEL services. USSD CAMEL Subscription Information (U-CSI) : The U-CSI identifies a set of subscriber specific mappings from a USSD service code to a gsmSCF address. USSD General CAMEL Service Information (UG-CSI) : The UG-CSI globally identifies a set of mappings from a USSD service code to a gsmSCF address. The global mapping applies to all HPLMN subscribers. If, for a particular service code, both U-CSI and UG-CSI are applicable then the U-CSI shall take precedence.
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Manish Das
CAMEL Subscription Information
• SMS-CSI: SMS-CSI contains subscription information for subscribers that require CAMEL support of MO SMS. SMS-CSI is transferred to the VLR or to the SGSN on Location Update and Restore Data or when SMS-CSI has changed. GPRS-CSI: When processing GPRS Attach requests for subscribers requiring CAMEL support, the SGSN receives a GPRS-CSI from the HLR, indicating the SGSN to request instructions from the gprsSSF. The SGSN monitors on request the GPRS events and informs the gprsSSF of these events during processing, enabling the gprsSSF to control the execution of the GPRS session or individual PDP contexts in the SGSN. M-CSI: The HLR contains Mobility management CAMEL Subscription Information (M-CSI) for those subscribers that require CAMEL control of Mobility Management events. M-CSI is sent to the VLR during the Location Update and Restore Data procedures or when M-CSI is modified in the HLR. The M-CSI is deleted in the VLR with the Delete Subscriber Data procedure.
Manish Das
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CAMEL Phases
• CAMEL has been evolving in several phases. • Finalized in 1997, CAMEL phase I introduced improved capabilities as mobile operators could begin to offer services and features to their customers that could work while roaming. • Phase I of CAMEL does not offer the ability to interact with the Specialized Resource Function (SRF). The SRF is a functional capability found in Voice Response Units (VRU). • In CAMEL phase I, a call is simply cutoff in progress when an account balance reaches zero.
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CAMEL Phases
• Completed in 1998, CAMEL phase II provided many additional capabilities, but perhaps the most significant is support for SRF which allows interaction with specialized network resources such as the Voice Response Unit (VRU). The VRU is an important network element for certain applications such as IN based mobile prepay service. • The VRU plays voice prompts during prepay account recharge and announcements such as a low balance warning before or during the cal to alert the subscriber of that condition. • On-line charging. • Expansion of the range of DPs.
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CAMEL Phases
CAMEL Phase III has been developed to support data services available through GPRS, EDGE and UMTS. CAMEL Phase III also supports
• Real time charging of SMS-MO while roaming. • Mobility Management. • SS notfication.
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Basic CAMEL Architecture (Phase I)
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Basic CAMEL Architecture (Phase I)
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Basic CAMEL Architecture (Phase II)
In the second phase the CAMEL feature supports: - mobile originated and forwarded calls - mobile terminating calls; - any time interrogation; - suppression of announcements; - announcements, in band user interaction; - charging features; - supplementary service invocation notifications; - USSD interaction with the gsmSCF.
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Basic CAMEL Architecture (Phase II)
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CAMEL Services
• • • • • • • Prepaid services Advice of charge though e-value Mid-call announcement VPN Free Phone Premium number Universal access number
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CAMEL Services
• The most popular services is Prepaid. • Prepaid is implemented with some additional components.
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Trend in Prepaid subscription
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Non-IN Prepaid Technology
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Non-IN Prepaid Technology
1. Customer initiates a call 2. MSC detects that the caller uses prepaid account and sets up a voice channel to service node 3. Service node asks from the prepaid billing platform (PBP) if the call should be allowed 4. If call is allowed, a second voice channel is established from service node trough MSC to the called party • This method costs one extra voice channel compared to IN prepaid.
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Non-IN Prepaid Technology
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Prepaid system architecture
GUI SMS
Script Management Graphical User Interface
SCP
Call Control
PPAS
Administrative System Voucher Data & Management
SDP- PrePaid
Network
Rating Engine Account, Service Class and Tariff Data
IVR
Refill Inquiries
MSC/SSF
AST/DR - Announcements
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HLR
IN Architecture Elements
Service Switching Point (SSP) – Major function of the SSP is to detect events during call processing, called triggers, that indicate an IN call event – After triggering, the SSP suspends call processing and starts a series of transactions with the SCP to determine the handling of the call – Supervises the length of the call
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IN Architecture Elements
Service Control Point (SCP) Contains the IN service logic. Control of call handling – Call redirection guidance (Free phone) – call duration – Real time charging – announcement control
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IN Architecture Elements
Intelligent Peripheral (IP) – Performs specialized resource functions such as: – Playing announcements – Collecting digits – Speech recognition – Recording and storing voice messages – Facsimile services... – Under the control of service logic of SCP.
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SDP – description
Central node in the PrePaid network It is the actual real-time rating engine, handles account deduction, tariffs and service class
SDP
Service Data Point
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PPAS – description
Hosts all subscriber and voucher administrative functions, such as:
• • • • • voucher maintenance refill and inquiries subscriber provisioning account lifecycle with expiry dates service class data
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CAMEL Call Processing • MSC call processing model
– Basic call state models (BCSMs) • Originating call model • Terminating call model
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CAMEL Call Processing (O-BCSM Phase I)
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CAMEL Call Processing (O-BCSM Phase I)
CAMEL Detection Point DP2 Collected_Info Description Indication that the O-CSI is active and analysed. The dialled number is received, but not analysed. Indication that the call is accepted and answered by the terminating party. A disconnect indication is received from the originating or the terminating party. Either calling or called party disconnection is informed to the gsmSCF.
DP7 O_Answer
DP9 O_Disconnect
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CAMEL Call Processing
Data sent to SCP after InitialDP detection:
- Event met; - IMSI; - Calling Party’s Number; - Calling Party’s Category; - Service Key; - Location information of the calling subscriber; - ISDN Bearer Capability; - High Layer Compatibility; - Basic Service Code; - Called Party BCD Number. - Call identification information; - Time and Time Zone information
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CAMEL Call Processing (O-BCSM Phase I)
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MSC Call Processing (T-BCSM Phase I)
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MSC Call Processing (T-BCSM Phase I)
CAMEL Detection Point DP12 Term._Attempt_Authorized DP15 T_Answer DP17 T_Disconnect Description Indication that the T-CSI is active and analysed. Call is accepted and answered by terminating party. A disconnect indication is received from the terminating or the originating party.
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CAMEL Call Processing (O-BCSM Phase II)
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CAMEL Call Processing (O-BCSM Phase II)
CAMEL Detection Point DP2 Collected_Info DP 4 Route_Select_Failure DP 5 O_Busy DP6 O_No_Answer DP7 O_Answer DP9 O_Disconnect Description Indication that the O-CSI is active and analysed. The dialled number is received, but not analysed. Indication that the call establishment failed Indication that a busy indication is received from the terminating party Indication that an application timer associated with the O_No_Answer DP expires Indication that the call is accepted and answered by the terminating party. A disconnect indication is received from the originating or the terminating party. Either calling or called party disconnection is informed to the gsmSCF. Indication that a disconnect indication is received from the originating party during the call establishment Procedure Not reachable event can be determined upon a cause IE in the ISUP release message.
Manish Das
DP 10 O_Abandon
DP 50 O_Not_Reachable
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CAMEL Call Processing - MOC
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CAMEL Call Processing - MOC
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CAMEL Call Processing
Examples of Pre-Call announcements could be: • Maximum allowed duration for the call • Low account balance warning, if applicable • Funds expiration warning, if applicable
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MSC Call Processing (T-BCSM Phase II)
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CAMEL Call Processing (T-BCSM Phase II)
CAMEL Detection Point DP12 DP 13 T_Busy DP 14 T_No_Answer DP15 T_Answer DP17 T_Disconnect DP 18 T_Abandon Description Term._Attempt_Authorized Indication that the T-CSI is active and analysed. Indication that a busy indication is received from the destination exchange Indication that an application timer associated with the T_No_Answer DP expires Call is accepted and answered by terminating party. A disconnect indication is received from the terminating or the originating party. A disconnect indication is received from the originating party during the call establishment procedure Not reachable or call establishment failure event can be determined from the HLR or upon a cause IE in the ISUP release message.
DP 51 T_Not_Reachable
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CAMEL Call Processing (T-BCSM Phase II)
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CAMEL Call Processing - MTC
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CAMEL Call Processing –disconnection upon fund expiry
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CAMEL Call Processing - MTC
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SMS MO
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SMS MO
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SMS MO using GPRS
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SMS MO State Model
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SMS MO State Model
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GPRS through CAMEL Phase III
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SGSN - Successful GPRS Data Transfer- User Disconnects
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SGSN - Successful GPRS Data Transfer - Funds Expiry
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Real time charging
With CAMEL phase 1 no real time charging was possible. With CAMEL phase 2 when a call is successfully established, the SCP instructs the underlying network to allow the call for a given time and to contact the SCP/CSE for further instructions or to release the call immediately after the given time. But real time charging of SMS-MO while roaming is possible in CAMEL phase 3 only.
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Typical Prepaid Implementation
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Prepaid account replenishment options Replenishment of an account can be undertaken in a variety of ways: Through the application of a phone card (voucher) through the IP, IVR or USSD Through a credit card or ATM transaction Through a web interface with a credit card Through the system GUI by a Calling Center representative
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CAMEL Abbreviations
• • • • • • • • • • • • • BCSM DP EDP GMSC gsmSCF gsmSSF HPLMN IPLMN O-CSI OSS SLPI TDP VPLMN Basic Call State Model Detection Point Event Detection Point Gateway MSC GSM Service Control Function GSM Service Switching Function Home PLMN Interrogating PLMN Originating CAMEL Subscription Information Operator Specific Service Service Logic Program Instance Trigger Detection Point Visited PLMN
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Manish Das
THANK YOU
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Manish Das