[Freeswitch-users] DTMF bleed through in conference

[David Bolen]

Avi Marcus <avi at avimarcus.net> writes:

> Could this be a keypad sound that gets picked up by the microphone?

Yeah, I considered that (wouldn't be the first time I've confused
things while running experiments with a bunch of microphones and
outputs next to each other), but in past tests, I've muted all input
devices in the conference, and still hear it.  Not sure I remembered
to do that in the test in my last message, so I just re-ran it, with
both blink and the PAP2T analog phone muted, and it still occurred.

In taking it one step further though, if the leg using DTMF is muted
at the conference level (either via the cli or invoking mute through
the DTMF bindings), then while DTMF is still recognized, nothing makes
it to other participants.  Which I guess either means something really
is in-band (which doesn't explain my rtp pcap being silent, plus if
in-band I'd expect to hear the full tone, since blink, which no analog
DTMF detector should be all or nothing) or that flag is indirectly
covering up the issue by avoiding whatever processing is putting the
glitch on the other participant leg. I'll probably try adding some
debugging to mod_conference at a few points to see if I can at least
identify where it thinks the audio may be coming from (or at least
confirm it thinks there is audio on the muted channel).

-- David