Re: [splices] Using Two Separate Devices to Start a Conversation proposal

Gonzalo Camarillo <> Tue, 21 June 2011 08:10 UTC

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Date: Tue, 21 Jun 2011 11:09:21 +0300
From: Gonzalo Camarillo <>
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Subject: Re: [splices] Using Two Separate Devices to Start a Conversation proposal
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Hi Alan,

>> As Dale mentioned, this also depends on the other end doing the "right
>> thing" with this case. It is a leap of faith to assume it will realize it
>> should accept both streams and use one for input and the other for output.
>> ISTM its at least as likely that it would accept the first stream, reject
>> the second, and then have only a one-way "conversation".
> OK, I understand the problem right now.  The problem is that this is a
> special kind of "Join" operation.  It is kind of a join, but not
> quite.
> The operation we are after is perhaps similar to 3.3.8 Far-Fork in RFC 5850:
> I suspect instead of Join, we need a new primitive, lets call it
> Splice or Merge which requests the UAS to add the media in the INVITE
> into the dialog that is referenced.

Yes... this is exactly what we proposed 5 years ago in one of the drafts
that, eventually, led to the creation of the SPLICES WG:

The idea was that the media streams of a given session could be
established using more than one SIP dialog.

Note that most SPLICES-related discussions up to a couple of months ago
were based on the fact that such a mechanism (i.e., using different
dialogs to establish a single session) would require support from the
remote end point. That is also the point Paul made in his comment above.
I personally would be OK with a mechanism along these lines, though.