[SIPForum-discussion] what is the advantage of sending SDP in ACK?

[Rosen, Brian]

First remember:
UAC sends INVITE
UAS sends OK
UAC sends ACK

SDP negotiation has two parts: offer and answer.

SIP allows either UAC to send offer and UAS to send answer or for UAS to send offer and UAC to send answer. Although its more common for UAC to send the offer, it's possible for the UAC to not send an offer in the INVITE. In that case, the UAS will send the offer in the OK and then the UAC will send the answer in the ACK.

So while UAC -> Offer in INVITE
UAS -> Answer in OK is common

UAC no offer in INVITE
UAS -> Offer in OK
UAC -> Answer in ACK is possible

Brian
--------------------------
Brian Rosen
NeuStar
(724) 382-1051
brian.rosen at neustar.biz


From: Varadhan M [mailto:m.varadhan at gmail.com]
Sent: Tuesday, June 12, 2012 02:45 AM
To: Amit Kumar <amit.chhikara at hotmail.com>
Cc: discussion at sipforum.org <discussion at sipforum.org>
Subject: Re: [SIPForum-discussion] what is the advantage of sending SDP in ACK?

Im not sure, so probably this could be an scenario where it might help

Invite with List of supported Media
200 Ok with list of supported media instead of 1
so may be ACK can help to find out the codec choose from the 200 OK


On Mon, Jun 11, 2012 at 11:49 AM, Amit Kumar <amit.chhikara at hotmail.com<mailto:amit.chhikara at hotmail.com>> wrote:
Hi all,


what is the advantage of sending SDP in ACK?


Thanks & regards

Amit

_______________________________________________
This is the SIP Forum discussion mailing list
TO UNSUBSCRIBE, or edit your delivery options, please visit http://sipforum.org/mailman/listinfo/discussion
Post to the list at discussion at sipforum.org<mailto:discussion at sipforum.org>


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sipforum.org/pipermail/discussion/attachments/20120612/5766d0bb/attachment-0002.html>