[Freeswitch-users] DTMF bleed through in conference

[David Bolen]

I'm encountering what I would probably best describe as some bleed
through of inbound DTMF when in a conference, and I was wondering if
anyone might have suggestions for likely causes or troubleshooting?

DTMF detection itself seems fine, and appears to properly be using
rfc2833 (the SDPs all show include "a=rtpmap:101 telephone-event/8000").
I get "RTP RECV DTMF" logs for each digit that is recognized.
However, a reasonable percentage of the time, some small fraction of
the DTMF appears to be heard by the conference as a whole.  Never the
whole thing, and sometimes it's a bit distorted (though that may just
be due to it being so short).  Almost as if a small portion of a sound
sample makes it through.

For testing, I'm using internal phones with direct SIP connections to
the switch so no PSTN or gateways involved, though it also occurs with
a PSTN caller coming in through multiple gateways.  For the internal
phones, I've tried both a physical phone through a PAP2T, as well as a
PC soft phone.

This is with git-868d823 from Jul 29, so a few weeks old but reviewing
the more recent commits there weren't any seemingly related to DTMF or
conferencing.

Any suggestions on places to look or things to try would be most
appreciated.

-- David