Re: [rtcweb] Question about JSEP createOffer

"Ravindran, Parthasarathi" <> Wed, 09 May 2012 06:25 UTC

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From: "Ravindran, Parthasarathi" <>
To: Roman Shpount <>, Justin Uberti <>
Thread-Topic: [rtcweb] Question about JSEP createOffer
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Date: Wed, 09 May 2012 06:24:59 +0000
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Subject: Re: [rtcweb] Question about JSEP createOffer
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I agree with Richard & Roman. "Full" re-OFFER MUST supported required for couple of mid session scenario like

1)      The session is established with audio and then video shall be added in the middle in case complete offer is provided in re-OFFER.

2)       It is possible to change the codec in the middle of the Session as Roman mentioned.

From: [] On Behalf Of Roman Shpount
Sent: Tuesday, May 08, 2012 9:03 PM
To: Justin Uberti
Subject: Re: [rtcweb] Question about JSEP createOffer

On Tue, May 8, 2012 at 10:46 AM, Justin Uberti <<>> wrote:

That is an interesting point. Could you give a short example of when such a "full" re-OFFER would be used? There are a few ways we could handle this case.

Actually I was the person who argued that "full" capabilities should be present in original SIP O/A, when new offer is generated in an existing session. The use case for this are B2BUA that connect an existing session to a new call or another existing session. Typically, B2BUA would ask one of the call parties for the offer (send an INVITE with no body in SIP), get the new offer, and send this offer to the newly placed call. In order for this to work, all the calling party capabilities should be listed in this new offer, in particular all the codecs and all the communications types (audio, video, text, etc), or call would not be successfully established.
Roman Shpount