Subject: RE: [SIP] Call-ID

From: "Maddux, Michel" <[email-masked]>
Date: Tue, 14 Nov 2000 15:35:14 -0600

What is the best method then, if Also is deprecated? thanks. /m.

Michel A. Maddux
Senior IP Architect

-----Original Message-----
From: Billy Biggs [mailto:[email-masked]]
Sent: Tuesday, November 14, 2000 7:54 AM
To: Mohammad Vakil
Cc: [email-masked]
Subject: Re: [SIP] Call-ID

Mohammad Vakil ([email-masked]):

> 2. If A wants to bring C into a conference call on a call going on
> with B, then it shouldn't generate a new call-id for C. A can invite C
> with a Also header telling B is also in a call, so C can also
> establish a signalling relationship with B.

  Sorry, but the use of the Also header has been deprecated.  I doubt
you will find anyone who implements this or ever intends to.  It has
been deemed a "bad idea".

-- 
Billy Biggs, 3Com               Email: [email-masked]
http://www.div8.net/billy/      Phone: [email-masked]

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From: Billy Biggs <[email-masked]>
Date: Tue, 14 Nov 2000 16:12:46 -0600

The scenario asked about was a distributed conference:

> > with B, then it shouldn't generate a new call-id for C. A can invite
> > C with a Also header telling B is also in a call, so C can also

  This form of conferencing, where each participant has a distinct
signalling relationship with each other, is difficult to manage.  It
seems that people are currently just implementing simpler forms of
conferences using MCUs, 3-Way calling, and handoff/transfer using REFER.

  Also was originally defined in the sip-cc-01 call control draft, which
is long expired.  It was not continued due to the complexity of the
draft, the many unresolved issues, and the dangerous overloading of
INVITE/BYE.

  Some further investigation was done by some folks at Dialogic in the
dmcs draft, but after discussion at the IETF, the 4th Bakeoff, and on
the mailing list, it was decided that further call control extensions be
defined more explicitly using new methods where applicable.  At least
that was my understanding.

  This philosophy is outlined in the Call Control Framework draft,
draft-campbell-sip-cc-framework-01.txt