mobile DTMF timing
mad at auth.se
Fri Jan 27 18:07:38 UTC 2012
> the timeout is set after the reception of the DTMF ACK. this ensures
> that the time to play the tone is at least 70ms. then the tones is
> stooped, and after it has been acked, the timer is started again to wait
> for the next tone. then the next tone, if any, is sent.
> see: http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling
> can you send me a log of the process when you send the dtmf tones?
Ok, I misread the dtmf_statemachine, I understand the 70ms are the minimum length a DTMF tone should last according to convention.
Actually I re-tested with this value and - of course - now it does work as expected.
Unfortunately I don't have the layer23 log anymore, but my first test calls rather seem to had some issue with the MSC not confirming the Start DTMF frame.
While changing the tone length value, the MSC might got responsive to that again and after testing, I draw a false conclusion. :)
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