RFC 3824 (rfc3824) - Page 2 of 16


Using E



Alternative Format: Original Text Document



RFC 3824                     SIPPING E.164                     June 2004


       6.2.  Processing the Selected NAPTR Record . . . . . . . . . .  9
   7.  Compatibility with RFC 3761. . . . . . . . . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
       9.1.  Normative References . . . . . . . . . . . . . . . . . . 11
       9.2.  Informative References . . . . . . . . . . . . . . . . . 12
   A.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 14
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 15
       Full Copyright Statement . . . . . . . . . . . . . . . . . . . 16

1.  Introduction

   ENUM (E.164 Number Mapping, RFC 3761 [1]) is a system that uses DNS
   (Domain Name Service, RFC 1034 [4]) in order to translate certain
   telephone numbers, like '+12025332600', into URIs (Uniform Resource
   Identifiers, RFC 2396 [9]), like 'sip:'.  ENUM
   exists primarily to facilitate the interconnection of systems that
   rely on telephone numbers with those that use URIs to route
   transactions.  E.164 [10] is the ITU-T standard international
   numbering plan, under which all globally-reachable telephone numbers
   are organized.

   SIP (Session Initiation Protocol, RFC 3261 [2]) is a text-based
   application protocol that allows two endpoints in the Internet to
   discover one another in order to exchange context information about a
   session they would like to share.  Common applications for SIP
   include Internet telephony, instant messaging, video, Internet
   gaming, and other forms of real-time communications.  SIP is a
   multi-service protocol capable of initiating sessions involving
   different forms of real-time communications simultaneously.

   The most widespread application for SIP today is Voice-over-IP
   (VoIP).  As such, there are a number of cases in which SIP
   applications are forced to contend with telephone numbers.
   Unfortunately, telephone numbers cannot be routing in accordance with
   the traditional DNS resolution procedures standardized for SIP (see
   [14]), which rely on SIP URIs.  ENUM provides a method for
   translating E.164 numbers into URIs, including potentially SIP URIs.
   This document therefore provides an account of how SIP can handle
   telephone numbers by making use of ENUM.  Guidelines are proposed for
   the authoring of the DNS records used by ENUM, and for client-side
   processing once these DNS records have been received.

   The guidelines in this document are oriented towards authoring and
   processing ENUM records specifically for SIP applications.  These
   guidelines assume that the reader is familiar with Naming Authority
   Pointer (NAPTR) records (RFC 3403 [6]) and ENUM (RFC 3761 [1]).  Only
   those aspects of NAPTR record authoring and processing that have



Peterson, et al.             Informational