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VoIP, Portability, and the Evolution of Addressing
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VoIP, Portability, and the Evolution of Addressing


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LNPA & Future of Numbering Working Groups

LNPA & Future of Numbering Working Groups

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  • Number must be in full E.164 format including Country Code
  • Transcript

    • 1. VoIP, Portability, and the Evolution of Addressing LNPA & Future of Numbering Working Groups April 14, 2005 Presented by Penn Pfautz
    • 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 update Carrier OSS NPA-NXX CLLI Assoc. Trunk Selection Trunking data
    • 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
      DNS Lookup sip:
    • 5. The Public ENUM Infrastructure $ORIGIN IN NS . 4.4 IN NS . … $ORIGIN IN NS . IN NS . … $ORIGIN IN NAPTR 100 10 "u" "E2U+SIP" "!^.*$!!" . Tier 0 (Country Code Registry) Tier 1 (Telephone Number Registry) Tier 2 (Application Information) International Implementation worked in IETF and ITU-T National Implementation worked in CC1 ENUM LLC and ENUM Forum (US) … ( (
    • 6. ENUM Call Flow Internet 794-867-5309 DNS MSC Carrier C MMSC Carrier A
    • 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,, MCI, SBC Laboratories, Sprint, Verizon, and BellSouth
      • ENUM in a domain other than 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