Dale Worley wrote:
> On Wed, 2008-12-10 at 13:32 +0530, Nabam Serbang wrote:
>> 1) If the offer being presented in 2xx (200 OK) for INVITE is not acceptable
>> by UAC, what would be the valid answer in that ACK? Remember this not
>> re-INVITE which will have prior SDP.
> 
> No doubt you can take the SDP in the 200, modify in slightly in a few
> places, and convert it into an SDP answer that is value *with respect to
> the SDP offer*.  Of course, since you are going to terminate the dialog
> immediately, it does not matter if the SDP answer has any relationship
> to the capabilities of the UA itself.

For instance, put 0.0.0.0 in a c= line. Then copy all the m-lines but 
set all the port numbers to zero. Put in valid value for o-line and any 
others that just must be there, and nothing else.

>> 2) if same offer is not acceptable by UAC, it means there is no media
>> streams. Why send valid answer in ACK  when offer is not acceptable ?
> 
> So that every SDP offer receives an SDP answer (except when the offer is
> in a request and the request receives a failure response).
> 
>> Again
>> sending BYE immediately means terminating the session? If you are sure to
>> terminate the session soon, why to send answer in ACK? Shouldn't UAS
>> consider that ACK has never been received and UAS send BYE rather than UAC?
> 
> If the UAC does not receive an ACK, it must resend the 200 until it
> receives an ACK.  The fact that one or both UAs has sent a BYE for the
> dialog does not change that rule.
> 
> Dale
> 
> 
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