Thanks a lot for so complete response. Please read inline:

2008/8/16 Bob Penfield <[EMAIL PROTECTED]>:
> A CANCEL is an attempt to terminate the INVITE transaction which would 
> terminate ALL early dialogs. A single BYE cannot be used to terminate ALL 
> early dialogs. If the UAC wishes to terminate a specific early dialog, then 
> it would send a BYE. The BYE would include the To and From tags which 
> uniquely identify the dialog. For example, if the UAC received 18x responses 
> (creating early dialogs), and it decided it preferred that the call not 
> continue/complete on one of those early dialogs, it could send a BYE and 
> terminate that one dialog.

This seems really complex, I'd like to see just one SIP implementation
capable of cancelling a concrete early-dialog instead of all (CANCEL).
I just can't see *real* utility for it in *real* world. :)



> RFC 3261 does require provisional responses that create dialogs to have a 
> Contact header, although it is not real clear about it.

It seems that 12.1 and 12.1.1 below treat dialog and early-dialog
together, calling them just "dialog", am I right?
If this is correct, then I understand from 12.1.1 that a 1XX (non 100)
MUST include a "Contact" header, mustn't it?


> Section 12.1 says:
>
>   Within this specification, only 2xx and 101-199 responses with a To tag,
>   where the request was INVITE, will establish a dialog.
>
> Sections 12.1.1 says:
>
>   When a UAS responds to a request with a response that establishes a
>   dialog (such as a 2xx to INVITE), the UAS MUST copy all Record-Route
>   header field values from the request into the response (including the
>   URIs, URI parameters, and any Record-Route header field parameters,
>   whether they are known or unknown to the UAS) and MUST maintain the
>   order of those values.  The UAS MUST add a Contact header field to
>   the response.



Really thanks for all. :)

PD: Since this seems a different issue than the original thread
question I'll create a new mail about it.





-- 
Iñaki Baz Castillo
<[EMAIL PROTECTED]>

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