Subject: [SIP] Hop to Hop forwarding of Invite responses in the call flows docum ent

From: Sekhar Banerjee <[email-masked]>
Date: Mon, 23 Apr 2001 18:41:48 -0700

Hi All,
	I was going through the call flows in
http://www.cs.columbia.edu/~hgs/sip/drafts/draft-ietf-sip-call-flows-03.txt
and the falure scenario under 3.2.1 is where I have a question. The
Unsuccssful SIP to SIP no answer call flow seems to imply that not only is
the CANCEL a hop to hop request but also the 487 response and the ACK are
hop to hop. I thought that 487 and ACK were end to end. Am I missing
something here ?

Thanks

Sekhar

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From: "Brett Tate" <[email-masked]>
Date: Mon, 23 Apr 2001 22:17:36 -0400

> hop to hop. I thought that 487 and ACK were end to end. Am I missing

As stated in third paragraph section 10.3.1 
of rfc2543bis-02 November 24, 2000,
"a proxy generates an ACK for non-2xx final 
responses."

Similar text is in section 12.4.