Subject: RE: [Sipping] Doubt in offer/answer model

From: Scott Godin <[email-masked]>
Date: Wed, 18 May 2005 08:16:00 -0400

It is acceptable to accept one media stream but not the other - by
specifying 0 in the port of the m= line.

Yes - an ACK should always be sent for an Invite response.

-----Original Message-----
From: Suganya [mailto:[email-masked]] 
Sent: Tuesday, May 17, 2005 7:58 AM
To: [email-masked]
Subject: [Sipping] Doubt in offer/answer model

Hi all,

Consider the following case in offer/answer model.

One UA supports an audio and a video while the other UA supports only
video
After negotiating, should the reply sent be 606- NOT ACCEPTABLE response
code with "WARNING" header telling media not accepted ?

If so, should ACK be received for 606, ie. for each negotiation should
ACK be sent?

Regards.

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_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
Use [email-masked] for new developments of core SIP

---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 18 May 2005 09:05:02 -0400

> specifying 0 in the port of the m= line.

I would add to this. In general it will maximize the opportunity for 
interoperability if the request is accepted with the media that are 
supported, and with other media rejected. However a UA is also free to 
refuse the call if it considers the combination of media offered to be 
unacceptable. This is a local judgement call.

But if the call is to be rejected for this reason, 606 is not the 
appropriate response, because that speaks for all endpoints, not just 
the one responding. The proper response would be 406.

	Paul