1. © 2004 AT&T, All Rights Reserved. The world’s networking company SM VoIP, Portability, and the Evolution of Addressing LNPA & Future of Numbering Working Groups April 14, 2005 Presented by Penn Pfautz

2. © 2005 AT&T, All Rights Reserved. 2 In a pre-LNP environment, call routing based on 6-digit (NPA-NXX) translation of destination number from LERG. In an LNP environment, call routing based on 6-digit (NPA-NXX) translation of a Location Routing Number (LRN). PSTN Routing Regional NPAC SMS Carrier LSMS LNP SCP Porting Carrier Switch NPA-NXX Routing tables Dialed Number LRN Telcordia LERG™ industry broadcast record updateCarrier OSS NPA-NXX CLLI Assoc. Trunk Selection Trunking data

3. © 2005 AT&T, All Rights Reserved. 3 Problem Statement & Solution Path As carrier networks evolve to IP how should routing (including portability) be handled? SIP is signaling protocol of choice; URIs which can be resolved to IP addresses are the elements of address specification Unification of routing functions for all numbers (including portability) should be the objective so as to minimize service provider costs Evolution of voice networks to IP and IP interconnection argues for an IP-based solution – e.g. some form of ENUM which was specifically designed to map E.164 numbers into URIs Current ATIS PTSC NI-NI document envisions ENUM as target Supports evolution away from code-based routing and associated limitations on numbering resource optimization

4. © 2005 AT&T, All Rights Reserved. 4 What is ENUM? Provides mapping from E.164 numbers to IP resources Defined by IETF in RFC 3761 Telephone number as domain name Built on top of DNS Look up returns URI Example: +1-973-236-6797 DNS Lookup 7.9.7.6.6.3.2.3.7.9.1.e164.arpa sip:sfisher@att.net sip: sfisher@verizon.com mailto:sfisher1@att.com mailto:steve_fisher@yahoo.com

5. © 2005 AT&T, All Rights Reserved. 5 The Public ENUM Infrastructure $ORIGIN e164.arpa. 3.7.9.1 IN NS nsnanp.enum.com. 4.4 IN NS sweden_enum.com. … $ORIGIN 3.7.9.1.e164.arpa. 7.9.7.6.6.3.2 IN NS e164.att.net. 8.9.7.6.6.3.2 IN NS e164.xyz.com. … $ORIGIN 7.9.7.6.6.3.2.3.7.9.1.e164.arpa. IN NAPTR 100 10 "u" "E2U+SIP" "!^.*$!sip:19732366797@att.net!". e164.arpa Tier 0 (Country Code Registry) nsnanp.enum.com (3.7.9.1.e164.arpa) Tier 1 (Telephone Number Registry) e164.att.net Tier 2 (Application Information) International Implementation worked in IETF and ITU-T National Implementation worked in CC1 ENUM LLC and ENUM Forum (US) sweden_enum.com (4.4.e164.arpa) …

6. © 2005 AT&T, All Rights Reserved. 6 ENUM Call Flow MSC Carrier C MMSC Carrier A Internet 794-867-5309 9.0.3.5.7.6.8.4.9.7.1.e164.arpa sip:7948675309@carrierc.net mms:7948675309@carrierc.net DNS

7. © 2005 AT&T, All Rights Reserved. 7 Why ENUM? Built on fundamental IP technology – not legacy foundation Queries for URIs will come from IP network elements No plans exist to update existing NP architecture (e.g. TRQ1-3) to make use of URIs Distributed database, not SMS download ENUM operates at a 10-digit level obviating the need for a separate portability correction ENUM can support both end user and carrier provision of IP routing info Many VoIP providers do not directly obtain numbering resources and so, not being code or block holders, cannot provision the NPAC or LERG These are the carriers most likely to desire VoIP interconnection so their exclusion significantly limits scope of solution FCC SBCIS decision could alter this but may not given the uncertainties surrounding its implementation (terms & costs of interconnection; qualification for the ESP exemption ENUM can support both carrier specific interconnection and general “Internet” interconnection

8. © 2005 AT&T, All Rights Reserved. 8 ENUM Status Country Code 1 ENUM LLC planning RFP for Tier 1 Registry operator to be in service mid 2006 Country Code 1 ENUM LLC members include AT&T, GoDaddy.com, MCI, SBC Laboratories, Sprint, Verizon, and BellSouth ENUM in a domain other than e164.arpa can be rapidly implemented by a group of carriers should the public ENUM effort encounter difficulties Some wireless carriers use private ENUM for message center identification today. Other private ENUM implementations also exist

9. © 2005 AT&T, All Rights Reserved. 9 Alternatives to ENUM As long as code-based routing remains, more efficient to tie specification of IP Point-of-Interface to CO code or switch CLLI and let LNP function normally to identify CO Code to be used in routing This could be done as enhancement of LERG or via other processes