Subject: [SIP] draft-ietf-sip-session-timer-02.txt

From: "Prato, Francesco" <[email-masked]>
Date: Fri, 1 Sep 2000 19:20:56 -0400

I have a question about the draft-ietf-sip-session-timer-02.txt

It is not clear to me the scenario where neither UA support the session
timer but SPS inserts a required header.

Let's take the following example:

the UAC sends an INVITE request which does not contain the supported header
(or when contained the tag TIMER is not present).
Now, let's suppose that "the proxy wishes to insist that the call is only
established if the UAS supports session timer, it MAY insert a Require
header into the request, with the value "timer". (from the draft)
Question-1: How does respond UAS? As the scenario described in 8.8 or with a
420 Bad Extension, or should UAS reject the call?
Question-2: How does react SPS in this case? In case of 8.8 should SPS
reject the call or should just ignore it?

I was not able to find in the draft any clear statement about that. 

TNX

Francesco

Francesco Prato
System Engineer
SIEMENS ICM
Boca Raton (Florida)

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---

From: Anders Kristensen <[email-masked]>
Date: Sat, 02 Sep 2000 02:03:10 +0200

> 420 Bad Extension, or should UAS reject the call?

If the UAS supports the timer extension it proceeds as usual, e.g.
alerting a user and accepting the INVITE as appropriate. If the UAS does
not support timers it MUST reject the request with a 420 as per the SIP
spec.

> reject the call or should just ignore it?

On receiving the response the proxy just acts as usual, i.e. forwards
the final response to the caller. Since in this case it's the proxy that
insists on using timers it will probably want to stay on the signaling
path and monitor the call leg for re-INVITEs refreshing the timer.

--
Anders Kristensen