RE: Last Call: <draft-ietf-sipcore-199-05.txt> (Session Initiation Protocol (SIP) Response Code for Indication of Terminated Dialog) to Proposed Standard

["Worley, Dale R (Dale)" <[e-mail]>]

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From: [e-mail] [[e-mail]] On Behalf Of Cullen Jennings [[e-mail]]

I am still not aware of any use case where this actually helps. I searched the IETF and WG lists for email with the subject draft-ietf-sipcore-199 and I do not see a single email that suggests there is support for this draft or the changes in it since the previous LC.
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I recall discussing the utility of 199 at one of the IETF meetings.  Indeed, I pushed Christer rather hard on the subject.  The primary use is situations where the SIP UAC is a gateway and has to allocate audio processors to each early dialog; 199 gives the downstream elements the ability to release the allocated processors when an early dialog ends, even though the UAC will not see the failure response for some time.

Since then, the proposal has gone through a number of changes that increase its value.  E.g., clarification of how it interacts with 100rel processing, ensuring it works correctly when non-199-aware SIP elements are present, providing warnings against likely errors by implementors, and allowing UACs to generate 199s on their own behalf.  (That latter is significant in the SIP environments I work with, as we put more responsibility on the UAs and make the proxies stateless.)

Dale