Subject: RE: The SIP INFO Method And Non Call Associated Signaling

From: "Bill Korbe" <[email-masked]>
Date: Wed, 27 Oct 1999 14:19:58 -0400

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

Internet-Drafts are also available by anonymous FTP. Login with the username
"anonymous" and a password of your e-mail address. After logging in,
type "cd internet-drafts" and then
	"get draft-ietf-sip-info-method-00.txt".

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---

From: Sean Olson <[email-masked]>
Date: Wed, 27 Oct 1999 15:49:46 -0500 (CDT)

> use straight TCP, use SIGTRAN, use a phantom SIP call with no bearer

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