Subject: Question on Call-Id

From: Marc Petit-Huguenin <[email-masked]>
Date: Thu, 25 Nov 1999 15:59:32 +0000

Hello,

I have a question about redirection:
When the SIP entity redirected (the entity that receive the 3xx) send
the new INVITE, does the Call-Id of this new INVITE must, should or may
be the same that the Call-Id in the first INVITE?

Call-flows in draft-ietf-mmusic-sip-new-00 or
draft-sparks-sip-service-examples-00 use the same Call-Id, but is this
mandatory?

My problem is that I need a mean to be sure that the redirect completes
and to achieve this I must correlate the two INVITEs. I have the same
problem with the transfer feature, but in this case, the token parameter
in the BYE also and the INVITE requested-by permits this correlation.

Thank you for your help.

Regards,

-- 
Marc Petit-Huguenin
Home: mailto:[email-masked]
Work: mailto:[email-masked]
"Everything I love is either immoral, illegal or makes you fat"

---

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 29 Nov 1999 02:12:10 -0500

> be the same that the Call-Id in the first INVITE?

If a proxy recurses, it MUST be the same Call-ID.

If a UAC acts on the redirection, I don't think the spec specifies what
to do. This is, in part, because you can't force the UAC to use the same
Call-ID. It can collect the Contact headers from the response, and
reformulate a brand new invite. In fact, if this data is presented to
the user at the UAC, the user can simply copy-paste the redirected URL
and create a new call to that URL. Thus, defining a service which relies
on having the same Call-ID in the new INVITE may be troubling even if
this is made a MUST strength.

-Jonathan R.
-- 
Jonathan D. Rosenberg                       200 Executive Drive
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