Subject: [Sip] RE: Multiple Refers (refer-02 draft)

From: Robert Sparks <[email-masked]>
Date: Fri, 9 Nov 2001 13:07:16 -0500

The current text does not prevent you from supplying the parameter in the
case
of only one REFER in a dialog. It only requires it in the presence of
multiples.
 
The text is written this way so that existing implementations would not have
to change.
You are correct that requiring the parameter in all cases would increase
uniformity, but
it burns bits for the normal use case. Multiple REFERs in a dialog (at least
for transfer)
aren't going to happen that often.
 
RjS

-----Original Message-----
From: Sriram Parameswar [mailto:[email-masked]]
Sent: Friday, November 09, 2001 11:19 AM
To: [email-masked]'; [email-masked]'
Subject: Multiple Refers (refer-02 draft)

Hi Robert, 

In my reading of section 3.5.3.3 (reproduced below for convenience)I take it
that the CSEQ param is sent in the event header of a NOTIFY only if more
than one REFER has been received.

Is this the interpretation? If so - I propose that we send the CSEQ of the
REFER back in every corresponding NOTIFY event header. This leads to
uniformity and does away with unnecessary special cases. 

If my interpretation is not correct - I request that you change the wording
to clarify it - I volunteer to send you the wording if you would like.

Best Regards, 

Sriram 

__________________________________________ 
Sriram Parameswar              Phone: 972-685-8540 
Interactive Multimedia Server (IMS) Fax: 972-685-3563 
Nortel Networks, Richardson USA  Email: [email-masked] 

---------------------------------------------------------------- 
3.5.3.3 Multiple REFER requests in a dialog 

   A REFER creates an implicit subscription sharing the dialog 
   identifers in the REFER request.  If more than one REFER is issued in 
   the same dialog (a second attempt at transferring a call for 
   example), the dialog identifiers do not provide enough information to 
   associate the resulting NOTIFYs with the proper REFER. 

   Thus, for the second and subsequent REFER requests a UA receives in a 
   given dialog, it MUST include a cseq parameter in the Event header 
   field of each NOTIFY containing the sequence number of the REFER this 
   NOTIFY is associated with.

---

From: Pekka Pessi <[email-masked]>
Date: 10 Nov 2001 11:01:59 +0200

The Refer-To syntax uses URL, but URL is not defined by neither
	of the documents in References section.

	Should there be a reference to RFC 2396, too?  That would also
	mean using absoluteURI instead of URL. Of course, an application
	may support incomplete URLs.

					Pekka

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