Subject: [SIP] Re: summary: DTMF and voice-over-packet

From: "Serban Tatu" <[email-masked]>
Date: Fri, 21 Jul 2000 08:47:24 -0700

Sorry for picking up this thread again, but after reading the messages for the
last couple of weeks, it seems to me that:

1. There is no unique standard way of marrying DTMF and SIP, and regardless of
which method you pick (RTP or INFO method), you're bound to get in trouble. Is
it worth trying to support both? Any other ones?

2. Some people say that RTP/RFC2833 is the way to go. However, in the SIP Call
Flows Examples draft
(http://search.ietf.org/internet-drafts/draft-ietf-sip-call-flows-01.txt),
section 5.1. shows a DTMF digit carried by an INFO request. What's that thing
doing there?

Are there any devices (gateways or others) that speak SIP and deal with DTMF?
How does a SIP phone send DTMF digits to an IVR or an answering machine?

Any input appreciated, thanks,
Serban

---------------------------------------------
Serban Tatu
Starvision Multimedia
http://www.starvision.com/
---------------------------------------------

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 21 Jul 2000 12:08:32 -0400

> it worth trying to support both? Any other ones?

Our goal is to try and come to conclusion on this. The discussion seemed
to lean towards using rfc2833; objections were getting down to minor
issues which were related to current server implementations. You claim
both can get you into trouble. Can you elaborate on that?

> section 5.1. shows a DTMF digit carried by an INFO request. What's that thing

Oops. That needs to go. The call flows draft should only be referencing
standard approaches for message flows.

> How does a SIP phone send DTMF digits to an IVR or an answering machine?

Right now, the same way the telephone network does it. Encoded in the
audio stream.

-Jonathan R.

-- 
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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From: "Serban Tatu" <[email-masked]>
Date: Fri, 21 Jul 2000 09:04:48 -0700

----- Original Message -----
From: Jonathan Rosenberg <[email-masked]>
To: Serban Tatu <[email-masked]>
Cc: <[email-masked]>
Sent: Friday, July 21, 2000 9:08 AM
Subject: Re: [SIP] Re: summary: DTMF and voice-over-packet

> both can get you into trouble. Can you elaborate on that?

I guess what I meant is that if you pick one way and implement it, then there
will be some equipment that implements it the other way, and your box will not
interoperate with someone else's box. That's why I asked whether it's worth
implementing both...

Thanks,
Serban

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 21 Jul 2000 12:22:39 -0400

> interoperate with someone else's box. That's why I asked whether it's worth

Then half of the implementations are implementing proprietary protocols.

-Jonathan R.

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From: Alan Johnston <[email-masked]>
Date: Fri, 28 Jul 2000 16:22:51 -0500

> standard approaches for message flows.

I'll remove that example and add in a different example of an INFO request.
Suggestions for call flows are always greatly appreciated.

Alan Johnston
WorldCom.