Interworking ISDN Call Control User Information with SIP
RFC 7434

Internet Engineering Task Force (IETF)                     K. Drage, Ed.
Request for Comments: 7434                                Alcatel-Lucent
Category: Standards Track                                    A. Johnston
ISSN: 2070-1721                                                    Avaya
                                                            January 2015

        Interworking ISDN Call Control User Information with SIP

Abstract

   The motivation and use cases for interworking and transporting User-
   to-User Information (UUI) from the ITU-T Digital Subscriber
   Signalling System No. 1 (DSS1) User-user information element within
   SIP are described in RFC 6567.  As networks move to SIP, it is
   important that applications requiring this data can continue to
   function in SIP networks as well as have the ability to interwork
   with this ISDN service for end-to-end transparency.  This document
   defines a usage (a new package called the ISDN UUI package) of the
   User-to-User header field to enable interworking with this ISDN
   service.

   This document covers interworking with both public ISDN and private
   ISDN capabilities, so the potential interworking with QSIG will also
   be addressed.

   The package is identified by the new value "isdn-uui" of the
   "purpose" header field parameter.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in 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/rfc7434.

Drage & Johnston             Standards Track                    [Page 1]
RFC 7434                  ISDN Call Control UUI             January 2015

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents
   1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Summary of the ISDN User-to-User Service  . . . . . . . . . .   3
     3.1.  The Service . . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Impacts of the ISDN Service on SIP Operation  . . . . . .   6
   4.  Relation to SIP-T . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Transition Away from ISDN . . . . . . . . . . . . . . . . . .   7
   6.  ISDN Usage of the User-to-User Header Field . . . . . . . . .   7
   7.  UAC Requirements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  UAS Requirements  . . . . . . . . . . . . . . . . . . . . . .  10
   9.  UUI Contents  . . . . . . . . . . . . . . . . . . . . . . . .  11
   10. Considerations for ISDN Interworking Gateways . . . . . . . .  12
   11. Coding Requirements . . . . . . . . . . . . . . . . . . . . .  12
   12. Media Feature Tag . . . . . . . . . . . . . . . . . . . . . .  13
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  14
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     15.2.  Informative References . . . . . . . . . . . . . . . . .  16
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

Drage & Johnston             Standards Track                    [Page 2]
RFC 7434                  ISDN Call Control UUI             January 2015

1.  Overview

   This document describes a usage of the User-to-User header field
   defined in [RFC7433] to enable the transport of UUI in ISDN
   interworking scenarios using SIP [RFC3261].  Specifically, this
   document discusses the interworking of the following items, which are
   call control related: ITU-T Recommendation Q.931 DSS1 User-user