Subject: [SIP] draft-manyfolks & use of 180 Ringing plus Session: qos

From: Rohan Mahy <[email-masked]>
Date: Thu, 20 Jul 2000 10:55:55 -0700

Hi,

I asked about use of 180 with the Session header back on the list before 
Adelaide and raised this as an issue there.  Jonathan agreed that 180 + 
Session: QoS was acceptable, and I did not hear any technical objection to 
its use.

The latest draft-manyfolks still references only 183/PRACK/200, COMET/200, 
then another round of 180/PRACK/200.  Permitting 180/PRACK/200 as an option 
would save a round of signaling for calls to native SIP phones, and I 
cannot see any negative effects.

Can you please incorporate this as an option in the next version of this 
document?  I am happy to provide sample flows.

thanks,
-rohan

 >>Date: Wed, 22 Mar 2000 19:22:32 -0800
 >>To: Jonathan Rosenberg <[email-masked]>
 >>From: Rohan Mahy <[email-masked]>
 >>Subject: Re: clarifications on 183 and "manyfolks" drafts
 >>Cc: William Marshall <[email-masked]>, 
[email-masked]
 >>
 >>At 09:23 PM 3/21/00 , Jonathan Rosenberg wrote:
 >>
 >>I am in agreement with Bill's assessment here. The idea is to keep the
 >>precondition mechanism independent of the underlying QoS protocol.
 >>
 >>However, I disagree that the Session header only makes sense for 183. I
 >>see no reason why. My view of the Session header is that it informs the
 >>UA that there is some dependency on signaling behavior because of the
 >>session. The QoS and security Session: tokens in a request indicate that
 >>the INVITE should not cause local alerting until the preconditions are
 >>met, and that a provisional response with SDP should be sent. The QoS
 >>and security Session: in the provisional response indicates a similar
 >>thing - don't do anything with this message until the preconditions are
 >>met. So, I would argue its OK to put a Session header in a 180, in which
 >>case ringing (signaled by 180) doesn't occur until the preconditions are
 >>met.
 >>
 >great.  this could save a whole cycle of 183/ PRACK/ 200 messages in some
 >circumstances.

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