Re: [Sipping] Fwd: [Fwd: WGLC ofdraft-ietf-sipping-service-examples-10.txt]

[worley at dworley.hsd1.ma.comcast.net (Dale R. Worley)]

   From: "Jeroen van Bemmel" <jbemmel at zonnet.nl>

   My interpretation was always that 181 could be sent without to-tag

That seems sensible to me, but the normative documents seem to forbid
it.

   If you add a to-tag, it becomes dialog-creating, and should also have a 
   Contact header. Furthermore, the UAC would probably send a BYE on this 
   dialog, and the proxy would have to make sure not to forward that BYE

True, I suppose that a Contact would be necessary.  But the 181 would
only create an early dialog, which would eventually time out.  The UAC
could send a BYE to dispose of it, and the proxy would be required to
virtually forward it to the virtual UAS, which would have to respond
200.  But the proxy can recognize such BYEs by their dialog
identifiers and contacts.

Perhaps we should amend RFC 3261 to allow call-progress responses
without to-tags?

Dale

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