Internet Engineering Task Force (IETF) A. Johnston
Request for Comments: 6567 Avaya
Category: Informational L. Liess
ISSN: 2070-1721 Deutsche Telekom AG
April 2012
Problem Statement and Requirements for
Transporting User-to-User Call Control Information in SIP
Abstract
This document introduces the transport of call control User-to-User
Information (UUI) using the Session Initiation Protocol (SIP) and
develops several requirements for a new SIP mechanism. Some SIP
sessions are established by or related to a non-SIP application.
This application may have information that needs to be transported
between the SIP User Agents during session establishment. In
addition to interworking with the Integrated Services Digital Network
(ISDN) UUI Service, this extension will also be used for native SIP
endpoints requiring application UUI.
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/rfc6567.
Copyright Notice
Copyright (c) 2012 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
Johnston & Liess Informational [Page 1]RFC 6567 SIP UUI Reqs April 2012
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. Overview ........................................................2
2. Use Cases .......................................................3
2.1. User Agent to User Agent ...................................3
2.2. Proxy Retargeting ..........................................4
2.3. Redirection ................................................4
2.4. Referral ...................................................5
3. Requirements ....................................................6
4. Security Considerations .........................................8
5. Acknowledgements ...............................................10
6. Informative References .........................................10
1. Overview
This document describes the transport of User-to-User Information
(UUI) during SIP [RFC3261] session setup. This section introduces
UUI and explains how it relates to SIP.
We define SIP UUI data as application-specific information that is
related to a session being established using SIP. It is assumed that
the application is running in both endpoints in a two-party session.
That is, the application interacts with both the User Agents in a SIP
session. In order to function properly, the application needs a
small piece of information, the UUI, to be transported at the time of
session establishment. This information is essentially opaque data
to SIP -- it is unrelated to SIP routing, authentication, or any
other SIP function. This application can be considered to be
operating at a higher layer on the protocol stack. As a result, SIP
should not interpret, understand, or perform any operations on the
UUI. Should this not be the case, then the information being
transported is not considered UUI, and another SIP-specific mechanism
will be needed to transport the information (such as a new header
field). In particular, this mechanism creates no requirements on
intermediaries such as proxies, Back-to-Back User Agents, and Session
Border Controllers.
UUI is defined this way for two reasons. First, this definition
supports a strict layering of protocols and data. Providing
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