Hi Varun,

If a stateful proxy has forked the INVITE, it might have created a
number of client transactions for each of the INVITEs sent to different
UASs. 
When the proxy receives a CANCEL for this INVITE, it sends a response
(200 OK) from the server transaction context itself. It must then
generate CANCELs to be sent for all the pending client transactions as
described in RFC 3261 Sec. 16.10:

<quote>
   While a CANCEL request is handled in a stateful proxy by its own
   server transaction, a new response context is not created for it.
   Instead, the proxy layer searches its existing response contexts for
   the server transaction handling the request associated with this
   CANCEL.  If a matching response context is found, the element MUST
   immediately return a 200 (OK) response to the CANCEL request.  In
   this case, the element is acting as a user agent server as defined in
   Section 8.2.  Furthermore, the element MUST generate CANCEL requests
   for all pending client transactions in the context as described in
   Section 16.7 step 10.
 </quote>

There is another scenario where the proxy has forked an INVITE and one
of the UASs sends back a final response. In this case, it has to send
CANCELs to all the other UASs as given in RFC 3261, Sec 16.7 step 10.


Regards,

Nishant

-----Original Message-----
From: varun [mailto:[EMAIL PROTECTED] 
Sent: Thursday, June 21, 2007 11:26 AM
To: Patel Nishant-JTPD86
Cc: [email protected]
Subject: RE: [Sip-implementors] BYE on early dialog

Hi,
If Cancel is send to a proxy for an Invite which has been forked by the
proxy, will the cancel also get forked and send to the differenet UAS.

Thanks
varun

--- Patel Nishant-JTPD86 <[EMAIL PROTECTED]> wrote:

> Hi Varun,
> 
> An INVITE that is forked can cause multiple dialogs to be established 
> with different UASs. If the UAC has sent an INVITE and wishes to 
> terminate the whole session, it can send a CANCEL.
> The CANCEL terminates
> the INVITE transaction and hence, all the early dialogs established 
> due to it are terminated.
> 
> If the UAC wants to only terminate specific early dialogs that are 
> created due to this INVITE, without terminating the whole session, it 
> can send BYEs to the specific UASs and terminate the early dialogs 
> with them.
> 
> Regards,
> 
> Nishant
> -----Original Message-----
> From: [EMAIL PROTECTED]
>
[mailto:[EMAIL PROTECTED]
> On Behalf Of
> varun
> Sent: Wednesday, June 20, 2007 12:18 PM
> To: [email protected]
> Subject: [Sip-implementors] BYE on early dialog
> 
> Hi,
> As per RC 3261, Section 15, the Caller UA can send a BYE even on a 
> early dialog which means even before getting a 200 OK, the caller can 
> send a BYE. Does thats sound right?
> Generally you would send CANCEL to terminate an early dialog(means you

> have got a provisional response like 180).
> 
> Thanks
> Varun
> 
> 
>        
>
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