RFC 3608 (rfc3608) - Page 1 of 17

Session Initiation Protocol (SIP) Extension Header Field for Service Route Discovery During Registration

Network Working Group                                          D. Willis
Request for Comments: 3608                              dynamicsoft Inc.
Category: Standards Track                                   B. Hoeneisen
                                                                  Switch
                                                            October 2003


       Session Initiation Protocol (SIP) Extension Header Field
            for Service Route Discovery During Registration

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document defines a Session Initiation Protocol (SIP) extension
   header field used in conjunction with responses to REGISTER requests
   to provide a mechanism by which a registrar may inform a registering
   user agent (UA) of a service route that the UA may use to request
   outbound services from the registrar's domain.

Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Background . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Discussion of Mechanism  . . . . . . . . . . . . . . . . . .   4
   4.  Applicability Statement  . . . . . . . . . . . . . . . . . .   5
   5.  Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Usage  . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
       6.1.  Procedures at the UA . . . . . . . . . . . . . . . . .   6
       6.2.  Procedures at the Proxy  . . . . . . . . . . . . . . .   7
       6.3.  Procedures at the Registrar  . . . . . . . . . . . . .   8
       6.4.  Examples of Usage  . . . . . . . . . . . . . . . . . .   9
             6.4.1.  Example of Mechanism in REGISTER Transaction .   9
             6.4.2.  Example of Mechanism in INVITE Transaction . .  12
   7.  Security Considerations  . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . .  15
   9.  Normative References . . . . . . . . . . . . . . . . . . . .  15
   10. Informative References . . . . . . . . . . . . . . . . . . .  15



Willis & Hoeneisen          Standards Track