Updates to Asserted Identity in the Session Initiation Protocol (SIP)
RFC 5876

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 09

Internet Engineering Task Force (IETF)                         J. Elwell
Request for Comments: 5876             Siemens Enterprise Communications
Updates: 3325                                                 April 2010
Category: Informational
ISSN: 2070-1721

 Updates to Asserted Identity in the Session Initiation Protocol (SIP)

Abstract

   The Session Initiation Protocol (SIP) has a mechanism for conveying
   the identity of the originator of a request by means of the
   P-Asserted-Identity and P-Preferred-Identity header fields.  These
   header fields are specified for use in requests using a number of SIP
   methods, in particular the INVITE method.  However, RFC 3325 does not
   specify the insertion of the P-Asserted-Identity header field by a
   trusted User Agent Client (UAC), does not specify the use of
   P-Asserted-Identity and P-Preferred-Identity header fields with
   certain SIP methods such as UPDATE, REGISTER, MESSAGE, and PUBLISH,
   and does not specify how to handle an unexpected number of URIs or
   unexpected URI schemes in these header fields.  This document extends
   RFC 3325 to cover these situations.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5876.

Elwell                        Informational                     [Page 1]
RFC 5876            Updates to SIP Asserted Identity          April 2010

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................4
   3. Discussion ......................................................4
      3.1. Inclusion of P-Asserted-Identity by a UAC ..................4
      3.2. Inclusion of P-Asserted-Identity in Any Request ............5
      3.3. Dialog Implications ........................................6
   4. Behaviour .......................................................6
      4.1. UAC Behaviour ..............................................7
      4.2. Proxy Behaviour ............................................7
      4.3. Registrar Behaviour ........................................7
      4.4. UAS Behaviour ..............................................8
      4.5. General Handling ...........................................8
   5. Security Considerations .........................................9
   6. Acknowledgements ...............................................10
   7. References .....................................................10
      7.1. Normative References ......................................10
      7.2. Informative References ....................................11

1.  Introduction

   The Session Initiation Protocol (SIP) is specified in RFC 3261
   [RFC3261].  RFC 3325 [RFC3325] specifies a mechanism for conveying
   the asserted identity of the originator of a SIP request within a
   Trust Domain.  This is achieved by means of the P-Asserted-Identity
   header field, which is specified for use in requests using a number
   of SIP methods, in particular the INVITE method.  In addition, the
   P-Preferred-Identity header field can be used to indicate a
   preference for which identity should be asserted when there is a
   choice.

Elwell                        Informational                     [Page 2]
RFC 5876            Updates to SIP Asserted Identity          April 2010

   RFC 3325 does not specify the insertion of the P-Asserted-Identity
   header field by a User Agent Client (UAC) in the same Trust Domain as
   the first proxy.  Also, RFC 3325 does not specify the use of the
   P-Asserted-Identity and P-Preferred-Identity header fields with
   certain SIP methods such as UPDATE [RFC3311], REGISTER, MESSAGE