Obtaining and Using Globally Routable User Agent URIs (GRUUs) in the Session Initiation Protocol (SIP)
RFC 5627

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Network Working Group                                       J. Rosenberg
Request for Comments: 5627                                 Cisco Systems
Category: Standards Track                                   October 2009

     Obtaining and Using Globally Routable User Agent URIs (GRUUs)
                in the Session Initiation Protocol (SIP)

Abstract

   Several applications of the Session Initiation Protocol (SIP) require
   a user agent (UA) to construct and distribute a URI that can be used
   by anyone on the Internet to route a call to that specific UA
   instance.  A URI that routes to a specific UA instance is called a
   Globally Routable UA URI (GRUU).  This document describes an
   extension to SIP for obtaining a GRUU from a registrar and for
   communicating a GRUU to a peer within a dialog.

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

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   document authors.  All rights reserved.

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Rosenberg                   Standards Track                     [Page 1]
RFC 5627                     GRUU Mechanism                 October 2009

   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Rosenberg                   Standards Track                     [Page 2]
RFC 5627                     GRUU Mechanism                 October 2009

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Overview of Operation  . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Structure of GRUUs . . . . . . . . . . . . . . . . . . . .  5
       3.1.1.  GRUUs That Expose the Underlying AOR . . . . . . . . .  6
       3.1.2.  GRUUs That Hide the Underlying AOR . . . . . . . . . .  6
     3.2.  Obtaining a GRUU . . . . . . . . . . . . . . . . . . . . .  7
     3.3.  Using a GRUU . . . . . . . . . . . . . . . . . . . . . . .  8
     3.4.  Dereferencing a GRUU . . . . . . . . . . . . . . . . . . .  8
   4.  User Agent Behavior  . . . . . . . . . . . . . . . . . . . . .  9
     4.1.  Generating a REGISTER Request  . . . . . . . . . . . . . .  9
     4.2.  Learning GRUUs from REGISTER Responses . . . . . . . . . . 10
     4.3.  Constructing a Self-Made GRUU  . . . . . . . . . . . . . . 11
     4.4.  Using One's Own GRUUs  . . . . . . . . . . . . . . . . . . 12
       4.4.1.  Considerations for Multiple AORs . . . . . . . . . . . 13
     4.5.  Dereferencing a GRUU . . . . . . . . . . . . . . . . . . . 14
     4.6.  Rendering GRUUs on a User Interface  . . . . . . . . . . . 14
   5.  Registrar Behavior . . . . . . . . . . . . . . . . . . . . . . 14
     5.1.  Processing a REGISTER Request  . . . . . . . . . . . . . . 14
     5.2.  Generating a REGISTER Response . . . . . . . . . . . . . . 16
     5.3.  Timing Out a Registration  . . . . . . . . . . . . . . . . 16
     5.4.  Creation of a GRUU . . . . . . . . . . . . . . . . . . . . 17
     5.5.  Registration Event Support . . . . . . . . . . . . . . . . 19
   6.  Proxy Behavior . . . . . . . . . . . . . . . . . . . . . . . . 19
     6.1.  Request Targeting  . . . . . . . . . . . . . . . . . . . . 19
     6.2.  Record-Routing . . . . . . . . . . . . . . . . . . . . . . 21
   7.  Grammar  . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
   8.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 23