Re: dtmf relay in SIP?
"Krishna Sai" <ksai@bigfoot.com> Tue, 03 August 1999 14:02 UTC
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Reply-To: Krishna Sai <ksai@bigfoot.com>
From: Krishna Sai <ksai@bigfoot.com>
To: Jacob Avraham <jacoba@mediagate.co.il>, confctrl@ISI.EDU
Subject: Re: dtmf relay in SIP?
Date: Tue, 03 Aug 1999 10:01:28 -0400
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The avt (audio/video transport) group works on these issues. In particular, refer to drafts like : http://www.ietf.org/internet-drafts/draft-ietf-avt-dtmf-01.txt http://www.ietf.org/internet-drafts/draft-ietf-avt-tones-00.txt regards, Krishna Sai ECI Telecom -----Original Message----- From: Jacob Avraham <jacoba@mediagate.co.il> To: confctrl@ISI.EDU <confctrl@ISI.EDU> Date: Tuesday, August 03, 1999 5:44 AM Subject: RE: dtmf relay in SIP? > > > >I'm curious about DTMF in-band within the RTP stream. My audio guys tell me >that once the audio is encoded with something like G.723 or some other >vocoder, you loose the tone frequency info and it's almost impossible >to get accurate detection of DTMF. >Possibly, one could change RTP payload mid-stream to something like G.711 >but that's not always feasible (and forbidden by other protocols like >H323). >Any real world experience with this issue? > >Thanks, > >Jacob Avraham >Mediagate >> >> This configuration is a classic case of where RTP encapsulation is best. >> I'm personally unconvinced about dtmf transport in SIP in general; here >> its definitely not needed. >> >> Thanks, >> Jonathan R. >> >> gonzalo.camarillo@lmf.ericsson.se wrote: >> > >> > Hi, >> > >> > > If I have a regular telephone connected to a SIP enabled gateway and >calls >> > > another telephone with similar connection, is there anyway I can do >dtmf >> > > relay between the two phones in the SIP network? That is, when the >gateway >> > > receives a dtmf tone from the connected telephone, how does the >gateway send >> > > out the dtmf tone in a SIP message? >> > >> > You can use either the SIP INFO method or just encode the DTMF tones in >RTP >> > packets... >> > >> > Regards, >> > >> > Gonzalo > >
- dtmf relay in SIP? Wing Man Kwok
- dtmf relay in SIP? gonzalo.camarillo
- Re: dtmf relay in SIP? Jonathan Rosenberg
- RE: dtmf relay in SIP? Jacob Avraham
- Re: dtmf relay in SIP? Jonathan Rosenberg
- Re: dtmf relay in SIP? Krishna Sai
- Re: dtmf relay in SIP? Adam B. Roach