Subject: Re: DTMF signaling between media gateways - ouch!

From: "Pete Cordell" <[email-masked]>
Date: Tue, 23 Nov 1999 11:24:13 -0000

My feeling is that SIP stopped being purely an initiation protocol a long
time ago.  In fact, when the BYE method was added, it no longer was purely
an initiation protocol.  It went further down the path when all the call
transfer stuff was added.

I'm here because SIP is being touted as a solution for Internet Telephony,
which involves more, much more, than just initiation.  If that's not what
it's about a decision needs to be made quickly and the message that is being
spread by SIP advocates needs to be changed to avoid confusion in the market
place.

Pete

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

-----Original Message-----
From: Schroeder, Tim <[email-masked]>
To: [email-masked] <[email-masked]>
Date: 22 November 1999 23:44
Subject: RE: DTMF signaling between media gateways - ouch!

>I'm a bit confused by much of this DTMF discussion.  SIP is a Session
>Initiation Protocol, so it understands how to initiate sessions.  As for
the
>mid-call DTMF tones,
>
>(1) If they are coming from some network where those tones *do* have
session
>initiation implications, then the gateway ought to be able to map them to
>the existing set of SIP messages in some rational fashion.  So, in a
network
>where the DTMF 7 tone (R for record) means to add a recording device to the
>call, the SIP gateway would map this to an invite of a recording device to
>the call.
>
>(2) If those tones don't have session initiation implications, then I don't
>see why any of the SIP network servers would understand them (any more than
>a gateway would understand them); only the end systems would.  Yes, they
may
>be used for signaling, but it's not session initiation signaling, and I
>don't understand the desire to somehow wrap them up into SIP messages and
>send them between end systems that way.  I see SIP as being used to set up
a
>session between end systems, possibly consisting of two media channels, one
>used for end system signaling, one used for end system data.  I haven't
made
>the leap that because the end systems are interpreting some data as
>signaling, that the data should be sent using SIP messages.
>
>My impression from reading all the DTMF messages (and in trying to catch up
>-- there were a lot of them!) is that two separate kinds of signaling
>(session initiation, and some higher level service signaling) are being
>confused.  Currently SIP handles the first type.  Adding the INFO method
>might make it able to handle some of the second type, but I don't think it
>can handle all service signaling that easily.
>
>Tim Schroeder
>
>
>
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---

From: Henry Sinnreich <[email-masked]>
Date: Tue, 23 Nov 1999 07:24:46 -0600

Pete Cordell wrote
> I'm here because

Pete, if this is the reason for stuffing our mail, just say so and let's get
back to designing features we need for new services. As mentioned, telephony
legacy systems can be accommodated by gateway features and their ways need
not be ported to the Internet. I suggest we stop this thread, it's been a
drag already.

Henry

Henry Sinnreich
MCI WorldCom
400 International Parkway
Richardson, Texas 75081, USA

> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Pete Cordell
> Sent: Tuesday, November 23, 1999 5:24 AM
> To: Schroeder, Tim; [email-masked]
> Subject: Re: DTMF signaling between media gateways - ouch!
>
>