Re: [rtcweb] Working group last call for draft-ietf-rtcweb-audio

There has been sufficient indications that A-D has applications.
It would be odd to delete a small part of the RFC 4733 interoperability.

In RFC 4733, all are optional, and can be specified in SDP.
But if no fmtp is provided, then the whole set of DTMF tones shall be 
supported.

This is part of what RFC 4733 says about sdp:

  If the "events"
       parameter is omitted, support for events 0-15 (the DTMF tones) is
       assumed.

I suggest to stick to that and support the full set.

/Gunnar

Den 2015-12-19 kl. 15:12, skrev Matthew Kaufman:
> Two-way radio system gateways would benefit from having these tones available.
>
> Matthew Kaufman
>
> (Sent from my iPhone)
>
>> On Dec 19, 2015, at 7:43 AM, Bernard Aboba <bernard.aboba@gmail.com> wrote:
>>
>>> On Dec 18, 2015, at 20:12, Roman Shpount <roman@telurix.com> wrote:
>>>
>>> Because there are IVR systems that use them. They are much less common then IVR systems that use 0-9 * and # but they do exist. I have provided 4 examples of real IVR systems that use these tones. How many do you need to keep the extra tones? All these systems can probably be re-engineered not to use A-D tones, but since this is all legacy no one will spend the time.
>>>
>>> Your argument that these tones should be removed since they are sometimes blocked (When exactly? The only places I see them blocked are some international carriers) and would not work. The same applies to all DTMF tones. We should remove all telephone-events based on this logic.
>>>
>>> Most importantly I do not want optional tones. So, if we decide to remove A-D, they should not be allowed in the WebRTC API. If these tones are allowed in WebRTC API, everyone must implement them.
>> [BA] Bingo. To remove optional tones and discovery of tone capability, we either have to prohibit A-D or mandate that these tones be supported.
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Gunnar Hellström
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