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VoIP, Portability, and the Evolution of Addressing

Learn about the evolution of VoIP and portability, ENUM technology, SIP signaling protocol, and future numbering strategies. Find out how ENUM can support IP routing and influence carrier interconnection.

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VoIP, Portability, and the Evolution of Addressing

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  1. VoIP, Portability, and the Evolution of Addressing LNPA & Future of Numbering Working Groups April 14, 2005 Presented by Penn Pfautz

  2. PSTN Routing • 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). Porting Carrier Telcordia LERG™ Regional NPAC SMS NPA-NXX CLLI Assoc. industry broadcast Carrier LSMS Carrier OSS record update Trunking data LNP SCP Dialed Number LRN NPA-NXX Routing tables Switch Trunk Selection

  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. 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 Lookup 7.9.7.6.6.3.2.3.7.9.1.e164.arpa DNS sip:sfisher@att.net sip: sfisher@verizon.com mailto:sfisher1@att.com mailto:steve_fisher@yahoo.com

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

  6. MMSC Carrier A MSC Carrier C ENUM Call Flow Internet DNS 9.0.3.5.7.6.8.4.9.7.1.e164.arpa 794-867-5309 sip:7948675309@carrierc.net mms:7948675309@carrierc.net

  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. 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. 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

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