Subject: [Sip] Re-use of Call-ID in the SIP Replaces header

From: Jonathan Cumming <[email-masked]>
Date: Tue, 31 Jul 2001 13:18:48 +0100

Hi Billy

In section 2.2 of draft-biggs-sip-replaces-01, you specify that "A unique
call-id may be given to the replacement call.".  This seems unnecessarily
weak and could lead to interoperability problems where an application
assumes the re-use of the Call-ID.

If a unique Call-ID is required, as specified in RFC 2543, then why give the
end-point the option to re-use the existing Call-ID?

I suggest that "A unique call-id MUST be given to the replacement call".

Regards

Jonathan
---------------------------
Jonathan Cumming
DC-SIP Product Manager
Voice Networking Group
Data Connection Ltd
Tel:   +44 20 8366 1177          Fax: +44 20 8363 1039
Email: [email-masked]    Web: http://www.dataconnection.com

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---

From: Billy Biggs <[email-masked]>
Date: Tue, 31 Jul 2001 10:35:41 -0400

Jonathan Cumming ([email-masked]):

> In section 2.2 of draft-biggs-sip-replaces-01, you specify that "A
> unique call-id may be given to the replacement call.".  This seems
> unnecessarily weak and could lead to interoperability problems where
> an application assumes the re-use of the Call-ID.
> 
> If a unique Call-ID is required, as specified in RFC 2543, then why
> give the end-point the option to re-use the existing Call-ID?

  When we were first discussing methods of performing attended call
transfer, there was alot of discussion about using the Call-ID to
perform the replaces operation, that is, the replacement call (or
joining call) would be identified by having the same Call-ID as an
existing call.

  So, the text should really read "in our replaces model, a unique
call-id may be given to the replacement call, instead of previous models
which overloaded the meaning of the call-id".  I wasn't trying to
dictate behavior either way.

> I suggest that "A unique call-id MUST be given to the replacement

  Since this seems to be the modern consensus on the issue, I will
clarify this in the draft.

-- 
Billy Biggs                     [email-masked]
http://www.billybiggs.com/      [email-masked]