Andreas,
Please refer to Paul's post on this. The tags MUST be unique for a given
dialog, and cannot change with each provisional response.
As to your original question, when P sends INVITE to UA3, and UA3 sends
a 200 with a To tag, a new dialog is created with this new To tag in the
UAC. The early dialog established by the 18x from UA2 would be terminated
separately (might timeout at the UAC). This is a right way to implement CFNR
at P.
For more details on CFNR, refer to section 2.8 of
draft-ietf-sipping-service-examples-03.txt
-Kannan
PS: As for processing at P, the tags are ignored unless it is a call
stateful proxy.
----- Original Message -----
From: "Andreas Bystr�m" <[EMAIL PROTECTED]>
To: "Sip Implemators" <[EMAIL PROTECTED]>; "Sankaran
Narayanan" <[EMAIL PROTECTED]>
Sent: Monday, August 18, 2003 1:05 PM
Subject: RE: [Sip-implementors] To tag when forking requests
So it is possible for a UAS to change To tag in each provisional response it
send until it finaly sends a 200 OK, where that To tag need to be kept
during the dialog? And UAC must be able to update the remote tag value for
each provisional response and finaly set it permanent when it receives the
200 OK?
To clearify the sip messages sent: when the Proxy sends the cancel, it also
stops all responses from UA2, this so that no 487 should reach UA1 (the call
will in that case end).
// Andreas
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