Hi Folks,

I think the correct behavior is to send the CANCEL message, as per SIP RFC,
the cancel message is used for the cancelling the pending
request/transaction and then BYE, if you want to tear down the session.

Snippet from RFC 3261, section 9:

9 Canceling a Request

   The previous section has discussed general UA behavior for generating
   requests and processing responses for requests of all methods.  In
   this section, we discuss a general purpose method, called CANCEL.

   The CANCEL request, as the name implies, is used to cancel a previous
   request sent by a client.  Specifically, it asks the UAS to cease
   processing the request and to generate an error response to that
   request.  CANCEL has no effect on a request to which a UAS has
   already given a final response.  Because of this, it is most useful
   to CANCEL requests to which it can take a server long time to
   respond.  For this reason, CANCEL is best for INVITE requests, which
   can take a long time to generate a response.  In that usage, a UAS
   that receives a CANCEL request for an INVITE, but has not yet sent a
   final response, would "stop ringing", and then respond to the INVITE

   with a specific error response (a 487).




Cheers,
Aman



On Fri, Jun 8, 2012 at 2:35 PM, Tarun2 Gupta <[email protected]>wrote:

> Ravi
>
> My requirement is to clear the call since the immediate proxy is down and
> not responding. My Application is sending Cancel for the ReInvite
> immediately followed by Bye.
>
> So the correct behavior is to just send a Bye in case of a timeout?
>
> Regards,
> Tarun Gupta
> Aricent
>
> -----Original Message-----
> From: Ravi Kumar [mailto:[email protected]]
> Sent: Friday, June 08, 2012 2:21 PM
> To: Tarun2 Gupta; 'SIP'
> Subject: RE: [Sip-implementors] ReInvite times out, should a Cancel be
> sent or not
>
> Hi Tarun,
> If your intention is to ternimate call then CANCEL request is not required
> to send, because CANCEL request will cancel INVITE transaction (for
> re-invite will not cause call termination).
>
> Also as per RFC CANCEL request is to cancel INVITE transaction and in your
> case it has timeout then which transaction your application wants to
> cancel.
> Because timeout means peer has not processed request and UAC should not
> expect any response.
>
> RFC 3261
> 14.1 UAC Behavior
>
>   If a UA receives a non-2xx final response to a re-INVITE, the session
>   parameters MUST remain unchanged, as if no re-INVITE had been issued.
>   Note that, as stated in Section 12.2.1.2, if the non-2xx final
>   response is a 481 (Call/Transaction Does Not Exist), or a 408
>   (Request Timeout), or no response at all is received for the re-
>   INVITE (that is, a timeout is returned by the INVITE client
>   transaction), the UAC will terminate the dialog.
>
>     For INVITE initiated dialogs, terminating the dialog consists of
>      sending a BYE.
>
>
> Is your application after sending CANCEL request it is waiting for response
> to CANCEL request and Re-INVITE request? Or send CANCEL request and then
> immediate send BYE request?
>
> Regards,
> Ravi Kumar
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of
> Tarun2
> Gupta
> Sent: Friday, June 08, 2012 1:20 PM
> To: SIP
> Subject: [Sip-implementors] ReInvite times out, should a Cancel be sent or
> not
>
> Hi
>
> Consider the following scenario:
>
>
>  1.  A and B are in stable call.
>  2.  A presses hook-flash, ReInvite for hold sent.
>  3.  A - B call put on hold.
>  4.  A presses hook-flash again, ReInvite for resume sent.
>  5.  B does not respond (it is down) and ReInvite times out.
>
> How should the call be terminated. Should a Cancel be sent for ReInvite
> followed by a Bye or Bye alone would suffice? At our end, A sends a Cancel
> for ReInvite followed by Bye. Is it incorrect behavior? Can you please give
> me some normative references to support your answer.
>
> Regards,
> Tarun Gupta
> Aricent
>
>
>
>
>
>
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