Subject: [SIP] question on draft-ietf-sip-cc-transfer-00.txt

From: "Jana" <[email-masked]>
Date: Fri, 11 Aug 2000 08:25:44 +0530

Hi

  I have a question on the cc draft.

In section  5.2.2     Variation 2 : Protects transfer target

Here in the call flow, when the transferor sends the REFER 
to transfer target, it uses a Call-ID of 2, to tie the REFER 
with the previous Invite sent. But when the transfer target
 sends an invite to the transferor, it uses a Call-ID
of 2, how would the transferor know that this is the call with
Call-ID of 1, that is on hold waiting to be transfered, and 
not a totally new call.

  This information may be desired, since the user may not want to
answer another call at this point of time?

Thanks
Jana

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From: "Robert Sparks" <[email-masked]>
Date: Sun, 20 Aug 2000 10:51:06 -0500

Jana writes:
> with the previous Invite sent.

To elaborate on "tie" - in the current version of the draft, REFERs
have to take place in the context of a session initiatied with an
INVITE. I had several people at the bakeoff argue that this is an
an unneccesary restriction (and I agree). The current plan is to
remove it.

>                                But when the transfer target

I assume you meant transferee everywhere you used transferor in
this paragraph.

> answer another call at this point of time?

In draft-sparks-sip-cc-transfer-00, the call-ID from the TRANSFER
(now REFER) was copied into the resulting INVITE. That behavior
was removed from this draft in favor of allowing the transferor to
suggest a call-id to use through the use of headers in the Refer-To:
URL (see the ABNF for SIP-URL). If the transferor (who, in this scenario,
wishes to protect the transfer target) wishes to allow the the transferee
to correlate the invites, it could include the original call-id in the
Refer-To: URL.

RjS