Subject: [Sip] Out-of-Band DTMF Relay

From: Sarvi Shanmugham <[email-masked]>
Date: Thu, 11 Jul 2002 11:15:58 -0700

Is there a draft or spec addressing how out-of-band DTMF relay should be
done in SIP.

Is there preference between the INFO message and a NOTIFY message  to
carry this out-of-band DTMF between 2 SIP end-points.

Thanks,
Sarvi

---

From: Jonathan Rosenberg <[email-masked]>
Date: Sun, 14 Jul 2002 23:33:46 +0900

> Is there a draft or spec addressing how out-of-band DTMF relay should be

This remains an active item of discussion. There are several drafts, 
which include:

http://search.ietf.org/internet-drafts/draft-rosenberg-sipping-markup-00.txt
http://search.ietf.org/internet-drafts/draft-fairlie-sipping-netapp-session-00.txt
http://search.ietf.org/internet-drafts/draft-culpepper-sip-key-events-01.txt

Unfortunately, there are many proprietary implementations for this as well.

> carry this out-of-band DTMF between 2 SIP end-points.

INFO is really bad. I think there is general agreement on that. It 
causes extra signaling even if no one cares, and is limite in scope to 
just DTMF. All of the above three drafts use some mechanism whereby a 
server asks the client for input, which is generally better.

There is, of course, rfc2833, which is ideal for end-to-end DTMF, such 
as between gateways or between a PC and a gateway.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
Chief Scientist                         First Floor
dynamicsoft                             East Hanover, NJ 07936
[email-masked]                 FAX: (973) 952-5050
http://www.jdrosen.net                  PH:  (973) 952-5000
http://www.dynamicsoft.com

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip