The IESG has approved the following document:
- 'A P-Served-User Header Field Parameter for Originating CDIV session
   case in Session Initiation Protocol (SIP)'
  (draft-ietf-sipcore-originating-cdiv-parameter-08.txt) as Informational RFC

This document is the product of the Session Initiation Protocol Core Working
Group.

The IESG contact persons are Adam Roach, Alexey Melnikov and Ben Campbell.

A URL of this Internet Draft is:
https://datatracker.ietf.org/doc/draft-ietf-sipcore-originating-cdiv-parameter/





Technical Summary

Within 3GPP-specified mobile networks, the SIP header field P-Served-User 
[RFC5502] conveys the identity of the served user, his/her registration state, 
and the session case between a SIP proxy known as a Serving Call Session 
Control Function (S-CSCF) and a SIP Application Server (AS). Any calls that a 
user places (originates) or receives (terminates) pass through the user's 
assigned S-CSCF. Each user has a user profile that informs the S-CSCF of which 
action to perform depending on the session direction (originating or 
terminating) and the user state (registered or not). RFC 5502 covers basic 
originating and terminating session cases, but does not cover the case of call 
diversion services (CDIV) when the session is re-targeted. Without a session 
case for originating after CDIV, a S-CSCF cannot trigger an originating service 
for the diverting user nor can an AS execute the procedures for this particular 
session case.

This document defines a new P-Served-User header field parameter, "orig-cdiv", 
which conveys the session case of an originating session after CDIV services 
have been invoked. This document also fixes the ABNF in RFC5502 and provides 
more guidance for using the P-Served-User header field.

Working Group Summary

This document started out in the DISPATCH working group. During discussions on 
list, the DISPATCH working group found issues with RFC 5502's ABNF for the 
P-Served-User header field, so this draft captures that feedback. While this 
draft was being discussed in DISPATCH, the SIPCORE charter was expanded 
slightly, and the DISPATCH chairs felt that this document should go SIPCORE to 
see if the WG wanted to take it on (originally the draft was going to go the 
AD-sponsored route). The WG accepted the work with lots of +1s to adopt. It 
received thorough feedback from a few of the participants, all of which was 
included. 

Document Quality

This addition to the P-Served-User header field will be implemented in 3GPP 
mobile networks, so multiple vendors will be implementing this draft.  The 
document's Acknowledgments section thanks reviewers who had significant 
feedback, and all feedback was addressed. Since the document updates the Header 
Fields sub-registry of the SIP Parameters registry by adding a reference, the 
designated expert Adam Roach looked at it and had no issues. 

Personnel

Document Shepherd: Jean Mahoney
Responsible Area Director: Ben Campbell

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