Subject: RE: [Sip] REFER failures

From: [email-masked]
Date: Mon, 2 Jul 2001 13:25:58 -0500

> From: Henning G. Schulzrinne [mailto:[email-masked]]
 
[Problem to be solved: how to distinguish if the referred party
or the referred-to party rejected a REFER.]

> One solution is that the NOTIFY always includes the full SIP response,
> so that it's clear what this refers to. For late failures of the REFER
> (rather than the request triggered by it), it would be the final
> response that would have been sent, e.g.,
> 
> SIP/2.0 603 Refused
> From: sender of REFER
> To: recipient of REFER
> Call-ID: of original REFER
> CSeq: something REFER

I see a couple of problems with this proposal. The first is that the
URI to which the remote party has been referred may be something other
than a SIP URL. So, while synthesizing a response like you describe
above may make some sense, creating a whole new message for the remote
service may be bizarre.

For example, I believe it reasonable for a implementation which can
accept REFERs to "ftp:" URLs to map "550 Requested action not taken"
to "404 Not Found," I think it's a bit ludicrous to expect this
implementation to then go and invent a variety of headers to tack
onto this 404 for the purposes of determining where the error occurred.

The second problem, I believe, stems from the fact that several
parties at the interim meeting expressed some strong privacy
concerns about being "required" to include response header information
in NOTIFY requests related to REFER.

I admire the problem, but think the proposed solution is a hack based
on a hack. I suspect we can do better.

/a

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