Subject: RE: [SIP] call-flow; each user has 2 UAs

From: Jonathan Rosenberg <[email-masked]>
Date: Sun, 10 Dec 2000 18:39:49 -0500

I agree here with Billy that 3pcc, using a master controller above the two
devices, is absolutely the right way to go. 

-Jonathan R.

---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

> -----Original Message-----
> From: Billy Biggs [mailto:[email-masked]]
> Sent: Tuesday, November 28, 2000 9:45 AM
> To: [email-masked]
> Cc: [email-masked]
> Subject: Re: [SIP] call-flow; each user has 2 UAs
> 
> 
> [email-masked] ([email-masked]):
> 
> > As a simple example, say that the two medias are audio and video
> > (although in real life, of course, an app/device with video 
> will also
> > likely have audio).
> > 
> > Jack                         Jill
> > Audio  <-------------------------------------------------> Audio
> > Video  <-------------------------------------------------> Video
> > 
> > The important point is that the Audio and Video devices are NOT
> > integrated and have separate UA's, yet we want all four apps/devices
> > to be joined in one "session", with Jack's audio talking to Jill's
> > audio, and Jack's video talking to Jill's video. Perhaps we 
> can assume
> > that Jack's audio and video both have the same SIP URL.
> 
>   The session you describe is an abstraction layer above a 
> SIP session.
> 
>   I see two ways of handling this:
> 
>         Remote               The first method is to have a SIP call
> 	  |  SIP             between the remote side and some
> 	Master               controller which communicates to the A and
>        /      \  ?           V apps and incorporates their addresses
>     Video    Audio           into a common SDP.  The master can be a
> 			     3pcc server if you use SIP to talk to A/V.
> 
>                              The second method is simply to have two
>          Remote              calls up, and use some other means of
>         |      | SIP         association higher up.  This may 
> simply be
>       Video   Audio          Jack telling Jill about the 
> other session,
>                              or some new header which flags the app
>                              telling it to associate the two calls.
> 
> > We need some sort of four-way session with proper use of SDP to
> > distinguish media types. To add two UA's on the UAS side, we need
> > forking with non-exclusive response from two UA's. We also have to
> > decide how to bring in two UA's on the UAC side.
> 
>   You don't need to get so complicated.
> 
> -- 
> Billy Biggs, 3Com               Email: [email-masked]
> http://www.div8.net/billy/      Phone: [email-masked]
> 
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