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					                                                                                     TSG-X.200302xx-xx




                                        3GPP2 TSG-X
TITLE:

Proposed Revision to Annex G of 07r1PN-3-0085-200

SOURCE:

James Yu                                             Tel: +1-571-434-5572
NeuStar, Inc.                                        Fax: +1-571-434-5401
46000 Center Oak Plaza, Sterling, VA 20166           email: james.yu@neustar.biz


ABSTRACT:

This contribution proposes the revision texts to Annex G and references [60] and [61] that
are referenced in Annex G.


RECOMMENDATION:

Review the proposed changes. If accepted, incorporate the proposed revision texts to Annex
G of 07r1PN-3-0085-200 and Section 2.




NeuStar, Inc. grants a free, irrevocable license to 3GPP2 and its Organizational Partners to
incorporate text or other copyrightable material contained in the contribution and any
modifications thereof in the creation of 3GPP2 publications; to copyright and sell in
Organizational Partner's name any Organizational Partner's standards publication even though it
may include all or portions of this contribution; and at the Organizational Partner's sole discretion
to permit others to reproduce in whole or in part such contribution or the resulting Organizational
Partner's standards publication. NeuStar, Inc. is also willing to grant licenses under such
contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for
purpose of practicing an Organizational Partner‟s standard which incorporates this contribution.

This document has been prepared by NeuStar, Inc. to assist the development of specifications by
3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a
binding proposal on NeuStar, Inc. NeuStar, Inc. specifically reserves the right to amend or
modify the material contained herein and to any intellectual property of NeuStar, Inc. other than
provided in the copyright statement above.
1.   Pages 116 through 118, Annex G

     The proposed changes to Annex G are shown below.

G.1. Introduction

     This section describes how the Naming Authority Pointer (NAPTR) Resource Records (RRs) associated
     with a MDN are provisioned and retrieved via DNS-ENUM under Wireless Number Portability (WNP)
     and non-WNP environment.

     It has been recognized in the industry that “End User ENUM” and “Carrier ENUM” should use different
     domain trees to avoid problems such as

     - Mingling an end user‟s NAPTR RRs with those of the end user‟s serving carrier.
     - Swapping the NAPTR RRs from the end user‟s old serving carrier to those from the new serving
       carrier at the Tier 2 Provider when the end user changes the telephony carrier while keeping the same
       phone number.
     - Who, the end user or the end user‟s serving carrier, decides the nameservers to use to host the NAPTR
       RRs? If the end user decides, what if the end user chooses low capacity and unreliable nameservers
       to host the NAPTR RRs?

     This section assumes that the carriers use the “Carrier ENUM” approach to address their needs. End
     user opt-in is not an issue in this case. “Carrier ENUM” implies that a domain tree other than e164.arpa
     is used. Normally, ENUM refers to the “End User ENUM” that uses “e164.arpa.” But this section
     treats ENUM as a specific Domain Name System (DNS) technology and the domain trees “mdn.biz”
     and “lrn.biz” are used in the examples.

G.2. ENUM Entities

     A few ENUM-related entities are defined below.

     - Tier 0 Registry: This is the entity that has the delegated authority to the “mdn.biz” zone. It has the
       nameserver (NS) RRs of the Tier 1 Registry for each country code in the “mdn.biz” zone.

     - Tier 1 Registry: This is the entity that has the delegated authority to the MDNs (i.e., ENUM domain
       names) in a specific country code under the “mdn.biz” zone. It has the NS RRs of the Tier 2 Registry
       for each MDN in that country.

     - Tier 2 Registry: This entity has the following two types:

       * Tier 2 Registry (Carrier): This is the entity that hosts the NAPTR RRs for a MDN this particular
         carrier currently serves.
       * Tier 2 Registry (CRH): This is the entity run by a carrier that is the code range holder (CRH) of a
         MDN that has ported out of that carrier. A carrier is the CRH of a code range if it was designated as
         the holder or owner of that code range.

       For a country that does not support WNP, the Tier 2 Registry (Carrier) is the same as the Tier 2
       Registry (CRH). For a country that supports WNP, the Tier 2 Registry (Carrier) and the Tier 2
       Registry (CRH) are the same for a non-ported number and are different for a ported number.

G.3. WNP

     Some countries support WNP while others do not. For those countries that support WNP, some use the
     centralized Number Portability Administration Center (NPAC) to manage the porting events among the



                                                                                              Page 2 of 11
      carriers or have a way for the interested parties to get all the porting information in a region or the whole
      country, while others don‟t. In the latter case, the new carrier that is to serve a ported MDN informs the
      CRH about the routing information for that MDN. In that case, the CRH is typically involved in routing
      the call or signaling message destined toward that MDN. In terms of the routing information, some
      countries use routing numbers (RNs) and others use routing prefixes (RPs).              A RN is a different
      number from the MDN and is used by the network to route the call or signaling message. A RP is
      usually placed before the MDN to make a new MDN for routing.

      For easier discussions, the following three scenarios are used to discuss the proposed DNS-ENUM
      implementations:

      A. Tier 1 Registry knows all the WNP information (e.g., from the NPAC or the CRHs who provide the
         information about their ported out numbers).
      B. Only Tier 2 Registry (CRH) knows the WNP information for the MDNs ported out of its code
         range.
      C. The country does not support WNP.

G.4. DNS-ENUM Scheme at the Code Range Level

      This scheme assumes that the carriers assign the NAPTR RRs at the code range or routing prefix (RP)
      level. In other words, all the MDNs in the same code range (e.g., 1-571-434) or RP share the same set
      of NAPTR RRs. Each NAPTR RR provides the URI associated with a code range or RP for a specific
      application (e.g., the domain name of the MMSC serving a code range or RP). The reason why the
      NAPTR RRs are not provisioned at the individual MDN level is to reduce the carriers‟ administrative
      efforts in managing the zone files at their Tier 2 Registry (Carrier) nameservers. Otherwise, every time
      there is a ported in number, the carrier has to update the zone file.

      One domain tree (e.g., mdn.biz) is used when the MDN is in the DNS query and the other (e.g.,lrn.biz) is
      used when the code range or RP is in the DNS query. “mdn.biz” and “lrn.biz” are used to explain the
      scheme in several examples. Appropriate domain tree names are to be determined by the industry. The
      role of the Tier 1 Registry is to redirect a query for a MDN under “mdn.biz” to an associated code range
      under “lrn.biz” by using the Canonical (CNAME) RR. For a non-ported MDN, the code range of the
      MDN is used under “lrn.biz.” For a ported MDN, the code range of the RNor RP associated with the
      ported MDN is used under “lrn.biz.” of the based on the NS RRs information provided by the CRH for
      a code range or RP. The Tier 2 Registry (Carriers) only deals with “lrn.biz” at the code ranges or RP
      level in their zone files.

      Figure G.1a shows the hierarchy of the nameservers used in handling the DNS-ENUM queries when the
      Tier 1 Registry has all the WNP information so that Tier 2 Registry (CRH) is not involved. Figure G.1b
      shows the hierarchy of the nameservers used in handling the DNS-ENUM queries when the Tier 1
      Registry has no WNP information and the Tier 2 Registry (CRH) is involved. The dashed line in Figure
      G.1b indicates that the Tier 2 Registry (Carrier) is actually found through the Tier 1 Registry via the
      “lrn.biz” domain tree.

G.4.1 Tier 1 Registry knows all the WNP information

      This section describes the proposed scheme for country codes such as “1” where Tier 1 Registry can get
      all the WNP information.

G.4.1.1 Key Information Provisioned at Tier 1 Registry and Tier 2 Registry (Carrier)

      Every CRH of a code range such as +1-202-533 provides the NS RRs associated with that code range
      under “lrn.biz” to the Tier 1 Registry. The first 7 digits including the country code 1 of a RN is also a
      code range. If that code range is only used for RN (e.g., no MDN is assigned out of that code range),
      then the carrier also needs to provide the NS RRs for that code range under “lrn.biz” to the Tier 1
      Registry. If RP instead of RN is used for routing, the NS RRs associated with each RP that is assigned
      to a carrier under “lrn.biz” is provided to the Tier 1 Registry.



                                                                                                  Page 3 of 11
                                                                               Root
                                   .


                                                                                Tier 0
                                mdn.biz
                                                                               Registry
                                lrn.biz




                                                                                Tier 1
 x.x.mdn.biz          …         1.mdn.biz         …         x.x.x.mdn.biz      Registry
  x.x.lrn.biz                    1.lrn.biz                   x.x.x.lrn.biz



                                                                                Tier 2
   3.3.5.2.0.2.1.lrn.biz
                                  …            4.4.5.2.0.2.1.lrn.biz           Registry
                                                                               [Carrier]


Figure G.1a. DNS-ENUM hierarchy when Tier 1 Registry has all the MNP information.




                                                                                Root
                                   .


                                                                                Tier 0
                                mdn.biz
                                                                               Registry
                                lrn.biz




  x.mdn.biz
   x.lrn.biz
                     …       c.c.mdn.biz
                              c.c.lrn.biz
                                                …          x.x.x.mdn.biz
                                                            x.x.x.lrn.biz
                                                                                Tier 1
                                                                               Registry




                                                                                Tier 2
z.z.z.x.x.x.c.c.mdn.biz        …             y.y.y.x.x.x.c.c.mdn.biz           Registry
                                                                                [CRH]



                                                                                Tier 2
                                             v.v.v.x.x.x.c.c.lrn.biz           Registry
                                                                               [Carrier]


Figure G.1b. DNS-ENUM hierarchy when Tier 1 Registry has no MNP information.




                                                                             Page 4 of 11
     There are many ways a Tier 1 Registry can support the DNS-ENUM queries. One implementation by
     the Tier 1 Registry to create the CNAME RR for a MDN is described below. Assume that +1-202-533-
     1234 is ported to a carrier with the RN of +1-202-544-0000. The Tier 1 Registry creates a CNAME RR
     for 4.3.2.1.3.3.5.2.0.2.1.mdn.biz to point to 4.4.5.2.0.2.1.lrn.biz. The Tier 1 Registry has a set of NS
     RRs for 4.4.5.2.0.2.1.lrn.biz based on the NS RRs provided by the Code Range Holder (CRH) of +1-
     202-544 code range. For non-ported MDNs in the +1-202-533 code range, they all have the same
     CNAME RR that points to 3.3.5.2.0.2.1.lrn.biz. Again, the Tier 1 Registry has the set of NS RRs
     provided by the CRH of +1-202-533 under lrn.biz.

     When +1-202-533-1234 is ported to another carrier other than the CRH and the Tier 1 Registry receives
     the new RN (e.g., +1-202-566) or RP information for the ported MDN, it updates the CNAME RR for
     4.3.2.1.3.3.5.2.0.2.1.mdn.biz in the zone file to point to 6.6.5.2.0.2.1.lrn.biz.

     If a MDN, +1-202-533-4567, is ported out of the CRH to another carrier with the RN of +1-202-577, the
     Tier 1 Registry will update the CNAME RR for 7.6.5.4.3.3.5.2.0.2.1.mdn.biz in the zone file to point to
     7.7.5.2.0.2.1.lrn.biz.

     If +1-202-533-1234 is ported back to the CRH, the Tier 1 Registry will update the zone file by using
     3.3.5.2.0.2.1.lrn.biz in the CNAME RR for 4.3.2.1.3.3.5.2.0.2.1.mdn.biz.

     The Tier 2 Registry (Carrier) provisions the NAPTR RRs in the nameservers identified by the NS RRs
     in the Tier 1 Registry for each served code range or RP under “lrn.biz.” One of the NAPTR RRs would
     be for the MMS. Please note that the NAPTR RRs in the zone files are relatively stable because they
     are associated with the code range (e.g., +1-202-533 or 3.3.5.2.0.2.1.lrn.biz). So the Time to Live
     (TTL) value of those NAPTR RRs can be set to a typical value (e.g., a few days or longer).

     The Tier 2 Registry (Carrier) can delete, add or update the NS RRs at the Tier 1 Registry when required.

     It is recommended that the Time to Live (TTL) value of the CNAME RRs at the Tier 1 Registry be set
     to zero when the porting events can happen at any time.

     The Tier 1 Registry and each Tier 2 Registry (Carrier) also may provision other information so that they
     can communicate over non-secure or secure links. That aspect is not discussed.

G.4.1.2 DNS-ENUM query handling

     The steps in handling a DNS-ENUM query shown in Figure G.2 are described below.

     1. The originator MMS Relay/Server generates a DNS-ENUM query requesting for the NAPTR RR for
        4.3.2.1.3.3.5.2.0.2.1.mdn.biz.
     2. The query may go through a root nameserver and/or a Tier 0 Registry‟s nameserver to reach a Tier 1
        Registry‟s nameserver. The Tier 1 Registry‟s nameserver returns the CNAME RR associated with
        4.3.2.1.3.3.5.2.0.2.1.mdn.biz and the NS RRs for 4.4.5.2.0.2.1.lrn.biz.
     3. The originator MMS Relay/Server sends the query to one of the nameservers in the NS RRs for the
        NAPTR RR of 4.4.5.2.0.2.1.lrn.biz.
     4. The query may go through a root nameserver, a Tier 0 Registry‟s nameserver and/or a Tier 1
        Registry‟s nameserver to reach a Tier 2 Registry‟s nameserver. The nameserver of the Tier 2
        Registry (Carrier) receives the query and responds with the NAPTR RRs associated with
        4.4.5.2.0.2.1.lrn.biz.
     5. The originator MMS Relay/Server retrieves the NAPTR RR associated with “mms,” finds out the IP
        address corresponding to the domain name in the URI and sends the MMS message to that IP
        address.




                                                                                              Page 5 of 11
                                                                                          Root




                                                                                         Tier 0
                                                                                        Registry


                                     1. 4.3.2.1.3.3.5.2.0.2.1.mdn.biz
      Orig.
      MMSC
                                         2. CNAME RR & NS RRs                      Tier 1 Registry
                                           3. 4.
                                                 4.5.2
                                                      .0.2.1
                                                            .lrn.b
                                          4. N                     iz
                                               APTR
                                                       RRs
                                                                                     Tier 2 Registry
                                                                                        (Carrier)


         Figure G.2. DNS-ENUM query handling when Tier 1 Registry has all the MNP information.


G.4.2 Tier 2 Registry (CRH) involved in DNS-ENUM process

      This section describes the proposed scheme for country codes where Tier 1 Registry does not have the
      WNP information. All DNS-ENUM queries must go through the Tier 2 Registry (CRH) before
      reaching the Tier 2 Registry (Carrier).

G.4.2.1 Key Information Provisioned at Tier 1 Registry, Tier 2 Registry (CRH) and Tier 2 Registry
       (Carrier)

      Every CRH of a code range such as +CC-xxx-yyy that has the MDNs out of that code range assigned to
      the subscribers provides the NS RRs associated with that code range under “mdn.biz” and “lrn.biz”
      respectively to the Tier 1 Registry. It is likely that the same set of NS RRs for a code range under
      “mdn.biz” is used for the same code range under ““lrn.biz.” If that is always the case, the carriers would
      only provide the NS RRs for a code range under “mdn.biz” to the Tier 1 Registry, which will
      automatically generate the NS RRs for that code range under ““lrn.biz.” Since the Tier 1 Registry does
      not know any RN or RP information, there is no need to provide the NS RRs associated with the RP or
      RN.

      The Tier 1 Registry creates a set of NS RRs for each code range under “mdn.biz” or “lrn.biz.” The NS
      RRs are relatively stable so a typical TTL value can be used for the NS RRs.

      Each non-ported MDN under “mdn.biz” at the Tier 2 Registry (CRH) has a CNAME RR that points to
      the MDN‟s code range under “lrn.biz” (e.g., 9.8.7.3.3.3.1.1.1.c.c.mdn.biz is redirected to
      3.3.3.1.1.1.c.c.lrn.biz). It is recommended that the TTL value of the CNAME RRs at the Tier 2 Registry
      (CRH) be set to zero when the porting events can happen at any time

      When a carrier receives a ported-in MDN (e.g., +CC-111-333-789), it informs the Tier 2 Registry
      (CRH) about the RN or RP (e.g., +CC-222-444) for that MDN. The Tier 2 Registry (CRH) then updates
      the CNAME RR for 9.8.7.3.3.3.1.1.1.c.c.mdn.biz in the zone file to point to 4.4.4.2.2.2.c.c.lrn.biz.

      The Tier 2 Registry (CRH) is the one responsible for updating the CNAME RR associated with each of
      its ported-out MDN including the occasion when a ported-out MDN is ported back.



                                                                                                 Page 6 of 11
      The Tier 2 Registry (Carrier) provisions the NAPTR RRs in the nameservers identified by the NS RRs
      in the Tier 2 Registry (CRH) for each served code range or RP under ““lrn.biz.” One of the NAPTR
      RRs would be for the MMS. The NAPTR RRs are relatively stable so a typical TTL value can be used.

      The Tier 2 Registry (CRH) can delete, add or update the NS RRs under “mdn.biz” and “lrn.biz” at the
      Tier 1 Registry and the Tier 2 Registry (Carrier) update the RN or RP for a ported-in MDN at the Tier 2
      Registry (CRH) when required.

      A Tier 1 Registry and each Tier 2 Registry (CRH) or a Tier 2 Registry (CRH) and each Tier 2 Registry
      (Carrier) also may provision other information so that they can communicate over non-secure or secure
      links.

G.4.2.2 DNS-ENUM query handling

      The steps in handling a DNS-ENUM query shown in Figure G.3 are described below.

      1. The originator MMS Relay/Server generates a DNS/DNS-ENUM query requesting for the NAPTR
          RR for 9.8.7.3.3.3.1.1.1.c.c.mdn.biz. The query may go through a root nameserver and/or a Tier 0
          Registry‟s nameserver to reach a Tier 1 Registry‟s nameserver.
      2. The Tier 1 Registry‟s nameserver returns the NS RRs associated with 3.3.3.1.1.1.c.c.mdn.biz.
      3. The originator MMS Relay/Server sends the query to one of the nameservers in the NS RRs.
      4. A nameserver of the Tier 2 Registry (CRH) receives the query and responds with the CNAME RR
          that redirects to 4.4.4.2.2.2.c.c.lrn.biz.
      5. The originator MMS Relay/Server sends the query for the NAPTR RR associated with
          4.4.4.2.2.2.c.c.lrn.biz. The query may go through a root nameserver and/or a Tier 0 Registry‟s
          nameserver to reach a Tier 1 Registry‟s nameserver.
      6. A nameserver of the Tier 1 Registry receives the query and responds with the NS RRs associated
          with 4.4.4.2.2.2.c.c.lrn.biz.
      7. The originator MMS Relay/Server sends the query to one of the nameservers in the NS RRs.
      8. A nameserver of the Tier 2 Registry (Carrier) returns the NAPTR RRs associated with
          4.4.4.2.2.2.c.c.lrn.biz.
      9. The originator MMS Relay/Server retrieves the NAPTR RR associated with “mms,” finds out the IP
          address corresponding to the domain name and sends the MMS message to that IP address.

G.4.3 No WNP

      This section describes the proposed scheme for country codes where WNP is not supported. In this
      case, the Tier 2 Registry (CRH) is the same as the Tier 2 Registry (Carrier). The Tier 2 Registry
      (Carrier) is used in the description.

G.4.3.1 Key Information Provisioned at Tier 1 Registry and Tier 2 Registry (Carrier)

      Again, every CRH of a code range such as +CC-xxx-yyy that has the MDNs out of that code range
      assigned to the subscribers provides the NS RRs associated with that code range under “lrn.biz” to the
      Tier 1 Registry. Since this country does not support WNP, no RN or RP and no NS RRs associated
      with the RN or RP are involved.

      The Tier 1 Registry creates a set of the NS RRs for each code range under “lrn.biz” pointing to the
      nameservers of the Tier 2 Registry (Carrier) of that code range. It also creates a CNAME RR for each
      MDN under “mdn.biz” pointing to the MDN‟s code range under ““lrn.biz.” The NS RRs and the
      CNAME RR are static so the TTL for those RRs can have a typical TTL value.

      The Tier 2 Registry (Carrier) provisions the NAPTR RRs in the nameservers identified by the NS RRs
      at the Tier 1 Registry for each served code range. One of the NAPTR RRs would be for the MMS. The
      NAPTR RRs can have a typical TTL value if the information does not change frequently.




                                                                                             Page 7 of 11
       The Tier 2 Registry (Carrier) can delete, add or update the NS RRs associated with a code range under
       “lrn.biz” at the Tier 1 Registry when required.

       A Tier 1 Registry and each Tier 2 Registry (Carrier) also may provision other information so that they
       can communicate over non-secure or secure links.



                                                                                                    Root



                                                                                                  Tier 0
                                                                                                 Registry

                                          1. 9.8.7.3.3.3.1.1.1.c.c.mdn.biz

       Orig.                                           2. NS RRs
       MMSC                                    5. 4.4.4.2.2.2.c.c.lrn.biz                          Tier 1
                                                                                                  Registry
                                              3. 9.8.7           6. NS RRs
                                                       .3.3.3.1
                                                                 .1.1.c.c
                                                                           .mdn.b
                                                                                  iz
                                                   4. CN
                                                            AME R
                                                                      R                       Tier 2 Registry
                                                 7. 4
                                                      .4.4                                         (CRH)
                                                           .2.2
                                                                .2.c
                                                8. N                 .c.l
                                                                         rn.b
                                                     APT                      iz
                                                           RR
                                                                 Rs

                                                                                              Tier 2 Registry
                                                                                                 (Carrier)


         Figure G.3. DNS-ENUM query handling when Tier 1 Registry has no MNP information.


G.4.3.2 DNS-ENUM query handling

       The steps in handling a DNS-ENUM query are the same as those described in Section G.4.1.2 except
       that the ENUM domain name is different (e.g., the MDN is not in country code 1).


G.5. DNS-ENUM Recipient MDN Address Resolution Procedure

For those recipients MDN addresses that appear in an MM and belong to an external MMSE, the originator MMS
Relay/Server shall translate (resolve) them to a routable RFC 2822 [5] address that shall be used in the “RCPT TO”
SMTP subsequent commands.

DNS-ENUM recipient MDN address resolution procedure:

    1. The originator MMS Relay/Server shall ensure that the recipient address (MDN) complies with the E.164
       address format and includes the „+‟ character. In the case of national or local addressing scheme (e.g. only
       operator code followed by a number), the MMS Relay/Server shall convert the national or local number to an
       E.164 address format.

        EXAMPLE 1: +30-697-123-4567

        EXAMPLE 2: In case of number conversion 6971234567 in country code “30” is converted to
        +306971234567


                                                                                                     Page 8 of 11
2. The originator MMS Relay/Server shall remove all non-digit characters with the exception of the leading '+'.
   This string shall be used as the input to the NAPTR algorithm [60] by the originator MMS Relay/Server.

    EXAMPLE: +306971234567

3. The originator MMS Relay/Server shall remove all characters with the exception of digits.

    EXAMPLE: 306971234567

4. The originator MMS Relay/Server shall put dots (".") between each digit.

    EXAMPLE: 3.0.6.9.7.1.2.3.4.5.6.7

5. The originator MMS Relay/Server shall reverse the order of the digits.

    EXAMPLE: 7.6.5.4.3.2.1.7.9.6.0.3

6. The resulting subdomain (result of step 5) shall be converted to a FQDN by appending an appropriate string.
   The specific string depends on the administrative control of the ENUM implementation. The following
   example assumes that “mdn.biz” is used for a carrier ENUM implementation.

    EXAMPLES: 7.6.5.4.3.2.1.7.9.6.0.3.mdn.biz (non-e164.arpa domain).

7. The output may result in one of the following cases:
   a. E.164 number not in the numbering plan. The originating MMS Relay/Server shall invoke an appropriate
      address resolution exception handling procedure (e.g. send a message to the originating MMS User Agent
      reporting the error condition).

    b. E.164 number in the numbering plan, but no URIs exist for that number. The originating MMS
       Relay/Server shall invoke an appropriate address resolution exception handling procedure (e.g. send a
       message to the originating MMS User Agent reporting the error condition, perform the necessary
       conversion and route forward the message to the recipient via MM3, etc.).

    c. E.164 number in the numbering plan, but no MMS URIs (MMS URIs are of the form “mms:mailbox” and
       they are defined in the MMS Resource Record section) exist for that number. The originating MMS
       Relay/Server shall invoke an appropriate address resolution exception handling procedure (e.g. send a
       message to the originating MMS User Agent reporting the error condition, perform the necessary
       conversion and route forward the message to the recipient via MM3 using the appropriate URI based on the
       Service field, etc.).

   d. DNS ENUM service unavailable. The originating MMS Relay/Server shall invoke an appropriate address
      resolution exception handling procedure (e.g. send a message to the originating MMS User Agent reporting
      the error condition, store the message in the queue and retry at a later time, etc.).

   e. E.164 number in the numbering plan and MMS URIs exist for that number.

   EXAMPLE:       The following is an example of NAPTR Resource Records associated with the FQDN derived
                  from the recipient MDN address (+306971234567)

                  IN NAPTR 100 10 "u" " E2U+sip " "!^.*$!sip: sip.cosmote.gr!" .

                  IN NAPTR 100 11 "u" "E2U+mms"
                  "!^.*$!mms: TYPE=PLMN@mms.cosmote.gr!" .

                  IN NAPTR 101 10 "u" "E2U+mailto" "!^.*$!mailto: mycosmos.gr!" .

                  The +306971234567 is associated with the following URIs:

                  sip: sip.cosmote.gr

                  mms: TYPE=PLMN@mms.cosmote.gr

                  mailto: mycosmos.gr




                                                                                                 Page 9 of 11
    8. In case that the ENUM-DNS returns more than one MMS URI, the originator MMS Relay/Server shall sort the
       MMS URIs according to the Order and Preference fields as it is described in [60] and [61].

    9. The originator MMS Relay/Server shall resolve the domain part of the “mailbox” of the highest precedence
       MMS URI to an IP address using standard DNS.

        EXAMPLE: The highest precedence MMS URI is mms: TYPE=PLMN@mms.cosmote.gr

        The domain part of the “mailbox” is mms.cosmote.gr and is resolved (e.g. DNS) to 100.200.10.1

        The originator MMS Relay/Server shall create the mailbox address by adding the string in step 2 above to the
        beginning of the user part of the “mailbox.” If there is no user part before the addition (e.g., “mailbox” only
        contains the domain part), “@” will be added between the user part and domain part after the addition of the
        string to the user part.

        EXAMPLE: The mailbox address is +306971234567/TYPE=PLMN@mms.cosmote.gr

    10. The resulting IP address together with the recipient RFC 2822 address (“mailbox”) shall be used by the
        originator MMS Relay/Server for routing forward the MM using the protocol described in section 6.8 to the
        recipient MMS Relay/Server.

MMS Resource Record (RR)
The key fields in the NAPTR RR are the Domain, TTL, Class, Type, Order, Preference, Flags, Service, Regexp and
Replacement and they are described in [60] and [61]. In particular, for this release the following fields are further
specified as follows:

Service = "E2U+mms"

Regexp = "!^.*$!mms:mailbox!" where “mailbox” token and its associated formatting rules are specified in [5].

The MMS URI is of the form “mms:mailbox”



G.6. Discussions

       The administrative efforts by the Tier 2 Registry (Carrier) to maintain the zone files is minimum when
       the NAPTR RRs are allocated at the code range/RP level. Porting events will not require that the Tier 2
       Registry (Carrier) update the zone file.

       The Tier 2 Registry (Carrier) can provision the NAPTR RRs instead of the NS RRs at the Tier 1
       Registry or Tier 2 Registry (CRH) so that they are not even involved in the real-time DNS-ENUM
       queries.

       Also, using this scheme to locate the servers at the code range level, still allows the carriers to either
       address the MDN in the application layer (e.g., the SMTP) or formulate the Uniform Resource Locator
       (URL) such as the mms URL by including the MDN in the user part of the URL retrieved from a
       NAPTR RR. For example, if the domain name of the MMSC serving +306971234567 is
       mms.cosmote.com, the originator MMS Relay/Server can formulate the mms URL at the MDN level by putting
       the string “+306971234567” in the user part and adding “@” between the user part and the domain part to
       result in a mms URL of “mms:+306971234567@mms.cosmote.com.” The same can be done for a sip URL if
       “sip:sip.abcxyz.us” is retrieved from a NAPTR RR for a MDN of +1-202-533-1234. The sip URL at the
       MDN level can be formulated as sip:+1-202-533-1234@ sip.abcxyz.us.

       The DNS technology is well known and the infrastructure is out there. Once a Tier 1 Registry for a
       country is chosen, the NS RRs and the WNP information, if applicable, are incorporated into the
       nameservers of the Tier 1 Registry, the NS RRs are in the nameservers of the Tier 2 Registry (CRH)
       when applicable, and the NAPTR RRs are in the nameservers of the Tier 2 Registry (Carrier), the
       MMSC resolution based on the recipient MDN in that country can be done.




                                                                                                      Page 10 of 11
      Using the globally agreed domain tree names (e.g., “mdn.biz” and “lrn.biz”), any originator MMS
      Relay/Server can launch a DNS-ENUM query that contains a MDN under “mdn.biz” regardless of
      which country code that MDN resides and retrieve a set of NAPTR RRs associated with that MDN.
      There is no need to act differently based on whether the MDN is subject to WNP or dip the number
      portability (NP) database. The Tier 1 Registry or Tier 2 Registry (CRH) handles the WNP information
      during the DNS-ENUM resolution process.

      Additional NAPTR RRs can be defined using the same domain trees for other services/applications/uses
      such as:

      - The domain name of the Short Message Service Center (SMSC) or Message Center (MC) for a MDN.
        If desirable, additional information such as the system type (e.g., CDMA, TDMA, PCS1900, GSM,
        DCS1800, etc.) or protocol version can be defined.
      - The domain name of the Home Location Register (HLR) for a MDN.
      - The domain name of the location server for a MDN.
      - The RN or RP for a MDN (equivalent to a dip to the NP database)

      This infrastructure also can be used to retrieve Signaling System Number 7 (SS7) point code and/or
      subsystem number (PC/SSN) information associated with various services or network elements to
      reduce the traffic over SS7 network and/or the cost of SS7 message transport.


2.    Page 10, Section 2, References [60] and [61]

      The proposed changes are shown below.

[60] IETF, RFC 3403: “Dynamic Delegation Discovery System (DDDS) Part Three: The DNS Database”,
URL:
http://www.ietf.org/rfc/rfc3403.txt

[61] IETF, RFC 2916: “E.164 number and DNS”, URL: http://www.ietf.org/rfc/rfc2916.txt; and IETF,
draft-ietf-enum-rfc2916bis-03.txt, “The E.164 to URI DDDS Application (ENUM),” URL:
http://www.ietf.org/internet-drafts/draft-ietf-enum-rfc2916bis-03.txt




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