RFC 3515 (rfc3515) - Page 1 of 23

The Session Initiation Protocol (SIP) Refer Method

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Network Working Group                                          R. Sparks
Request for Comments: 3515                                   dynamicsoft
Category: Standards Track                                     April 2003


           The Session Initiation Protocol (SIP) Refer Method

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 the REFER method.  This Session Initiation
   Protocol (SIP) extension requests that the recipient REFER to a
   resource provided in the request.  It provides a mechanism allowing
   the party sending the REFER to be notified of the outcome of the
   referenced request.  This can be used to enable many applications,
   including call transfer.

   In addition to the REFER method, this document defines the the refer
   event package and the Refer-To request header.

Table of Contents

   1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  The REFER Method . . . . . . . . . . . . . . . . . . . . . .  3
       2.1  The Refer-To Header Field . . . . . . . . . . . . . . .  3
       2.2  Header Field Support for the REFER Method . . . . . . .  4
       2.3  Message Body Inclusion. . . . . . . . . . . . . . . . .  5
       2.4  Behavior of SIP User Agents . . . . . . . . . . . . . .  6
            2.4.1 Forming a REFER request . . . . . . . . . . . . .  6
            2.4.2 Processing a REFER request. . . . . . . . . . . .  6
            2.4.3 Accessing the Referred-to Resource. . . . . . . .  6
            2.4.4 Using SIP Events to Report the Results
                  of the Reference. . . . . . . . . . . . . . . . .  7
            2.4.5 The Body of the NOTIFY. . . . . . . . . . . . . .  8
            2.4.6 Multiple REFER Requests in a Dialog . . . . . . .  9
            2.4.7 Using the Subscription-State Header
                  Field with Event Refer. . . . . . . . . . . . . .  9



Sparks                      Standards Track
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