A new IETF working group has been proposed in the Real-time Applications and Infrastructure Area. The IESG has not made any determination as yet. The following draft charter was submitted, and is provided for informational purposes only. Please send your comments to the IESG mailing list (iesg@ietf.org) by Tuesday, June 29, 2010. Call Control UUI for SIP (cuss) -------------------------------------------------- Current Status: Proposed Working Group Last modified: 2010-06-21 Chair(s): TBD Real-time Applications and Infrastructure Area Director(s): Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com> Robert Sparks <rjsparks@nostrum.com> Real-time Applications and Infrastructure Area Advisor: Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com> Mailing Lists: TBD Description of Working Group: The Call Control UUI for SIP (CUSS) working group is chartered to define a Session Initiation Protocol (SIP) mechanism for transporting call-control related user-to-user information (UUI) between User Agents. The mechanism developed in this working group is applicable in the following situations: 1. The information is generated and consumed by an application using SIP during session setup but the application is not necessarily even SIP aware. 2. The behavior of SIP entities that support it is not significantly changed (as discussed in Section 4 of RFC 5727). 3. Generally only the User Agent Client (UAC) and User Agent Server (UAS) are interested in the information. 4. The information is expected to survive retargeting, redirection, and transfers. 5. SIP elements may need to apply policy about passing and screening the information. 6. Multi-vendor interoperability is important. This mechanism is not applicable in the following situations: 1. The behavior of SIP entities that support it is significantly changed (as discussed in Section 4 of RFC 5727). 2. The information is generated and consumed at the SIP layer by SIP elements. 3. SIP elements besides the UAC and UAS might be interested in consuming (beyond applying policy) the information. 4. There are specific privacy issues involved with the information being transported (e.g., geolocation or emergency-related information). User data of the mechanism will be clearly marked with the application, encoding, semantics, and content type, allowing policy to be applied by UAs. The working group will define the information that each application must specify to utilize the mechanism. This type of application-specific information will be specified in standards-track documents. One important application of this mechanism is interworking with the ISDN User to User Information Service. This application defined by ITU-T Q.931 is extensively deployed in the PSTN today supporting such applications as contact centers, call centers, and automatic call distributors (ACDs). A major barrier to the movement of these applications to SIP is the lack of a standard mechanism to transport this information in SIP. For interworking with ISDN, minimal information about the content of the UUI is available to the PSTN-SIP gateways. In this case only, the content will just indicate ISDN UUI Service 1 interworking rather than the actual content. Call control UUI is user information conveyed between user agents during call control operations. As a result, the information must be conveyed with the INVITE transaction, and must survive proxy retargeting, redirection, and transfers. The mechanism must utilize a minimum of SIP extensions since it will need to be supported by many simple SIP user agents such as PSTN gateways. The mechanism must interwork with the existing ISDN service but should also be extensible for use by other applications and non-ISDN protocols. Even though interworking with the PSTN is an important requirement, call control UUI can be exchanged between native SIP clients that do not have any ISUP support. Therefore, existing SIP-T encapsulation-based approaches defined in RFC3372 do not meet the requirements to transport this type of information. Mechanisms based on the SIP INFO method, RFC2976, will not be considered by the working group since the UUI contents carry information that must be conveyed during session setup at the user agent - the information must be conveyed with the INVITE transaction. The information must be passed with the session setup request (INVITE), responses to that INVITE, or session termination requests. As a result, it is not possible to use INFO in these cases. The group will produce: - A problem statement and requirements document for implementing a SIP call control UUI mechanism - A specification of the SIP extension to best meet those requirements. Goals and Milestones ==================== Sep 10 - Problem statement and requirements document to IESG (Informational) Mar 11 - SIP call control UUI specification to IESG (PS) _______________________________________________ IETF-Announce mailing list IETF-Announce@ietf.org https://www.ietf.org/mailman/listinfo/ietf-announce
