[Blink] DTMF not supported
ASikkema at office.unet.nl
Thu Jul 22 18:29:05 CEST 2010
> Dtmf is sent as signaling in the rtp stream. It does not have a
> 'duration' only inband dtmf (you can enable it in blink, it plays a
> wav file) can have a duration. The equipment you mention must read
> dtmf from the rtp stream, and it seems it does not do it properly.
RFC2833, 4.4, payload format:
The payload contains the following fields:
duration: The duration of the tone, measured in timestamp units.
The tone begins at the instant identified by the RTP
timestamp and lasts for the duration value.
It is a little arcane but I have seen it being used (Asterisk 1.0 IIRC)
and I'm sure the gateways into PSTN will honour the values. Sending
RFC2833 events can be quite a lot more complicated than just sending a
single message ;-)
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