Subject: [Sip] Questions about the SIP Replaces Header draft.

From: "Padhye, Chinmay" <[email-masked]>
Date: Wed, 5 Sep 2001 13:25:19 -0700

Hello,

	I have a few questions and comments regarding the SIP Replaces
Header draft -
http://www.softarmor.com/sipwg/drafts/draft-biggs-sip-replaces-01.txt.

1)	In section 3 the draft states -
	"The to-tag and from-tag parameters MUST be included in the Replaces
header, as they are required for unique call-leg matching."

	In section 4 the draft states -
	"If the Replaces header matches more than one call-leg, the user
agent MAY use the Referred-By header if present to attempt to match the call
with an appropriate call-leg, but should otherwise ignore the header."

	The REFER draft says that the Referred-By header is mandatory
(section 3.2 of REFER 01 draft). Hence the words "if present" in the above
statement must be removed. 

	I also have a question regarding this -
	
	a)	When will a Replaces header match more than one call-leg.
The statements in the section 3 and 4 seem to contradict each other.

2)	In section 4 of the draft it says - 
	
	"If the Replaces header matches an unestablished call leg, that it,
the INVITE request for the call has not received or been sent a final
response, the Replaces header MUST be ignored."

	The "it" is a typo and should be "is".

	My question is - 
	How will a Replaces header match an unestablished call leg when a
response has not been received for an INVITE?

3)	I think the figures shown with the examples do not conform to the
latest REFER draft. None of the figures show NOTIFY being used. 

4)	The reference to the cc draft - reference [4], is to the old draft.

Regards,

Chinmay

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From: Henry Chen <[email-masked]>
Date: Thu, 06 Sep 2001 15:39:51 -0500

More questions in line.

Henry

> response has not been received for an INVITE?

Can the SIP user agent cancel the unestablished call leg instead of ignoring the
Replaces header?
What is the reason behind to ignore Replaces header for an unestablished
matching call leg?

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From: Henry Chen <[email-masked]>
Date: Tue, 18 Sep 2001 10:11:57 -0500

Billy and Rick:

    Could you explain following question?

    Thanks,

Henry