Subject: The SIP INFO Method And Non Call Associated Signaling

From: "Bill Korbe" <[email-masked]>
Date: Wed, 27 Oct 1999 15:53:04 -0500

The SIP protocol handles the transport of session control information during
the setup and tear down stages of a SIP controlled session.  The SIP INFO
Method allows for the carrying of session related control information that
is generated during a session when there are no setup or teardown messages
available to carry the information.  

If there is no active session but control information related to a session
still needs to be exchanged (e.g., non call associated signaling) are there
thoughts on what is the best transport mechanism to use for this case (e.g.,
use straight TCP, use SIGTRAN, use a phantom SIP call with no bearer
channel)?

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Friday, October 22, 1999 3:59 AM
To: IETF-Announce
Cc: [email-masked]
Subject: SIP INFO Method IETF Spec 21-Oct-99

A New Internet-Draft is available from the on-line Internet-Drafts
directories.
This draft is a work item of the Session Initiation Protocol Working Group
of the IETF.

	Title		: The SIP INFO Method
	Author(s)	: S. Donovan
	Filename	: draft-ietf-sip-info-method-00.txt
	Pages		: 10
	Date		: 21-Oct-99
	
This document proposes an extension to the Session Initiation Proto-
col.  This extension adds the INFO method to the SIP protocol.  The
intent of the INFO method is to allow for the carrying of session
related control information that is generated during a session.  One
example of such session control information is ISUP and ISDN signal-
ing messages used to control telephony calls services.
Other example uses of the INFO method include the carrying of encoded
DTMF digits and the reporting of signal strength in a wireless mobil-
ity application.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-sip-info-method-00.txt

---

From: "Pete Cordell" <[email-masked]>
Date: Thu, 28 Oct 1999 13:30:28 +0100

Would it be possible to do an INVITE with a SDP part that contained no media
statements?  If UASs didn't like this they would reject the session, which
is the desired response in this case.  Exchanges between the UAs would use
the usual SIP INVITE and INFO messages etc.  I feel this is better than
using separate TCP/UDP connections as we'll probably end up inventing
another protocol altogether.

Pete

=============================================
Pete Cordell
[email-masked]
=============================================

-----Original Message-----
From: Sean Olson <[email-masked]>
To: [email-masked] <[email-masked]>;
[email-masked] <[email-masked]>
Date: 27 October 1999 22:00
Subject: RE: The SIP INFO Method And Non Call Associated Signaling

>I personally like the idea of using a separate SIP session for this.
>The key would be choosing an appropriate SDP to describe this.
>Unfortunately or fortunately depending on how you look at it, there is
>no currently documented way to describe arbitrary UDP/TCP sessions in the
>manner that the rtpmap media attribute can describe arbitrary RTP sessions.
>You could of course define some RTP profile for the control that you are
>thinking about. If you are talking about some traditional PSTN protocol
>(ISUP/Q.931/etc.) you are probably better off using SIGTRAN. Or you could
>use some extension attribute in the SDP that means this is a signalling
>session...
>
>-----------------------------------------------------------------
>Sean Olson            E-mail: [email-masked]
>Ericsson Inc.         Voice: (972) 583-5472
>                      FAX: (972) 669-0154
>
>
>