Control of Service Context using SIP Request-URI
RFC 3087

Document Type RFC - Informational (April 2001; No errata)
Last updated 2013-03-02
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Network Working Group                                        B. Campbell
Request for Comments: 3087                                     R. Sparks
Category: Informational                                      dynamicsoft
                                                              April 2001

            Control of Service Context using SIP Request-URI

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   This memo provides information for the Internet community.  It
   describes a useful way to conceptualize the use of the standard SIP
   (Session Initiation Protocol) Request-URI (Uniform Resource
   Identifier) that the authors and many members of the SIP community
   think is suitable as a convention.  It does not define any new
   protocol with respect to RFC 2543.

   In a conventional telephony environment, extended service
   applications often use call state information, such as calling party,
   called party, reason for forward, etc, to infer application context.
   In a SIP/2.0 call, much of this information may be either non-
   existent or unreliable.  This document proposes a mechanism to
   communicate context information to an application.  Under this
   proposal, a client or proxy can communicate context through the use
   of a distinctive Request-URI.  This document continues with examples
   of how this mechanism could be used in a voice mail application.

Campbell & Sparks            Informational                      [Page 1]
RFC 3087                  SIP Service Control                 April 2001

Table of Contents

   1.      Introduction . . . . . . . . . . . . . . . . . . . . . . .  3
   2.      Example Application  . . . . . . . . . . . . . . . . . . .  3
   2.1     Using URIs to Control Voice Mail Service Behavior  . . . .  3
   3.      Voice Mail Scenario Descriptions . . . . . . . . . . . . .  5
   3.1     Deposits . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.1.1   Direct Request to Deposit to a particular mailbox  . . . .  5
   3.1.1.1 SIP source . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.1.1.2 Arbitrary PSTN source  . . . . . . . . . . . . . . . . . .  5
   3.1.1.3 Recognized PSTN source . . . . . . . . . . . . . . . . . .  6
   3.1.2   Direct Request to Deposit, mailbox to be determined  . . .  6
   3.1.2.1 SIP source . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.1.2.2 PSTN source  . . . . . . . . . . . . . . . . . . . . . . .  6
   3.1.2.3 Indirect Request to Deposit, due to find-me proxy decision  6
   3.2     Retrievals . . . . . . . . . . . . . . . . . . . . . . . .  7
   3.2.1   Request to Retrieve from a particular mailbox  . . . . . .  7
   3.2.1.1 Trusted SIP source . . . . . . . . . . . . . . . . . . . .  7
   3.2.1.2 Authenticated SIP source . . . . . . . . . . . . . . . . .  7
   3.2.1.3 Unauthenticated SIP source . . . . . . . . . . . . . . . .  7
   3.2.1.4 PSTN source  . . . . . . . . . . . . . . . . . . . . . . .  7
   3.2.2   Request to Retrieve, mailbox to be determined  . . . . . .  7
   3.2.2.1 SIP source . . . . . . . . . . . . . . . . . . . . . . . .  7
   3.2.2.2 Arbitrary PSTN source  . . . . . . . . . . . . . . . . . .  8
   3.2.2.3 Recognized PSTN source . . . . . . . . . . . . . . . . . .  8
   4.      Voice Mail Call Flow Examples  . . . . . . . . . . . . . .  8
   4.1     Generic Scenario . . . . . . . . . . . . . . . . . . . . .  8
   4.1.1   Direct call to the voice mail system . . . . . . . . . . .  8
   4.2     Message Deposit Scenarios  . . . . . . . . . . . . . . . . 13
   4.2.1   Call to known subscriber forwarded on no answer  . . . . . 13
   4.2.2   Call to known subscriber forwarded on busy . . . . . . . . 19
   4.2.3   Direct call to a subscriber's mailbox  . . . . . . . . . . 24
   4.3     Message Retrieval Scenarios  . . . . . . . . . . . . . . . 29
   4.3.1   Call to retrieve messages believed to be from a known
           subscriber . . . . . . . . . . . . . . . . . . . . . . . . 29
   4.3.2   Call to retrieve messages from an authenticated subscriber 33
   5.      Security Considerations  . . . . . . . . . . . . . . . . . 38
   6.      Acknowledgments  . . . . . . . . . . . . . . . . . . . . . 38
           References . . . . . . . . . . . . . . . . . . . . . . . . 38
           Authors' Addresses . . . . . . . . . . . . . . . . . . . . 38
           Full Copyright Statement . . . . . . . . . . . . . . . . . 39

Campbell & Sparks            Informational                      [Page 2]
RFC 3087                  SIP Service Control                 April 2001

1. Introduction

   A communication service should make use of the information it has at
   hand when being accessed.  For example, in most current voice mail
   implementations, a subscriber retrieving messages from his own desk
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