Request for Comments: 4569
Internet Assigned Numbers Authority (IANA) Registration
of the Message Media Feature Tag
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 © The Internet Society (2006).
This document registers with the IANA a new media feature tag associated with the 'message' media type. This media feature tag indicates that a particular device supports 'message' as a streaming media type. Media feature tags can be used to route calls to devices that support certain features.
Table of Contents
1. Introduction ....................................................2 2. Security Considerations .........................................2 3. IANA Considerations .............................................2 4. Acknowledgements ................................................3 5. Normative References ............................................3
The Session Description Protocol (SDP) specification  defines a number of media types. RFC 3840  registers with the IANA media feature tags associated with all those media types except for the 'message' media type. This document registers a new media feature tag that is associated with the 'message' media type.
The reason why the 'message' media feature tag was not registered by RFC 3840 was that when RFC 3840 was published, the SDP specification was RFC 2327 . RFC 3840 defined media feature tags for all the media types defined by RFC 2327. However, RFC 2327 did not define the 'message' media type. This media type was defined by the revised SDP specification , which was published after RFC 3840.
2. Security Considerations
Section 11.1 of RFC 3840  discusses security considerations related to the use of media feature tags.
3. IANA Considerations
Media feature tag name: sip.message ASN.1 Identifier: 21
Summary of the media feature indicated by this tag: This feature tag indicates that the device supports message as a streaming media type.
Values appropriate for use with this feature tag: Boolean.
The feature tag is intended primarily for use in the following applications, protocols, services, or negotiation mechanisms: This feature tag is most useful in a communications application for describing the capabilities of a device, such as a phone or PDA.
Examples of typical use: Routing a call to a phone that can support session-based instant messaging.
Related standards or documents: RFC 4569.
Security Considerations: Security considerations for this media feature tag are discussed in Section 11.1 of RFC 3840.
The need for this registration was discussed with Jonathan Rosenberg, Colin Perkins, and Jon Peterson.
5. Normative References
 Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998.  Holtman, K., Mutz, A., and T. Hardie, "Media Feature Tag Registration Procedure", BCP 31, RFC 2506, March 1999.  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002.  Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)", RFC 3840, August 2004.  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006.
Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420 Finland EMail: Gonzalo.Camarillo@ericsson.com
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