Re: Mozilla/Cisco API Proposal: DTMF

On Jul 15, 2011, at 2:51 , Niklas Enbom wrote:

> SIP has too many ways of doing DTMF:
>   * Inband waveform
>   * RFC 4733
>   * SIP Notify
> 
> It would be great if webrtc could stick to one.
> 
> Niklas

Completely agree. The  RTCWeb WG at IETF is trying to make a set of recommendation for what the over the wire protocol choices should be. I and others have been arguing that 4733 is the one that should be used for this work. There has not been much disagreement about this so if I had to guess, I would say it is very likely that will end up being the IETF recommendation to the W3C. 

> 
> On Thu, Jul 14, 2011 at 3:40 PM, Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com> wrote:
> 
> 
> >On Tue, 12 Jul 2011, Cullen Jennings wrote:
> >>
> >> Just a side note, the best way to do DTMF (RFC 4733) is not as an audio
> >> tone but as a seperate coded for transering the data that keys werhe
> >> pressed.
> >
> >I'm all for supporting DTMF. It seems that the main use case would be
> >communicating with legacy systems (on the Web, one would presumably use a
> >native AJAX app or some such and only use audio/video conferencing to
> >speak to an actual human), so it seems one of our requirements here has to
> >be interoperability with the POTS, and thus with legacy SIP systems.
> >
> >How do legacy SIP systems support DTMF? We presumably have to do it the
> >same way.
> My understanding is that RFC 4733 is used (inserting a special payload carrying DTMF in the RTP stream).
> 


Cullen Jennings
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