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

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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