This has nothing to do with the RTCM. The
DTMF receiver is the same one that is used in all the
other
channel drivers for the other types of interfaces
also.
When the app_rpt stuff was first being developed (10+
years ago), the default parameters
for the DTMF receiver seemed too "tight" for radio
use. There were a number of combinations
that were found of receivers and transmitting devices
(HT's mobiles, etc) that did not seem to
work reliably with the parameters the way they were,
so we developed the "RADIO_RELAX" set
of parameters, which are more "relaxed" then the
normal ones.
As time has gone on, there have been cases where using
these "relaxed" parameters have seemed
to do more harm then good. I dont know if your case is
one of those. If you wish to try, I suggest
re-compiling Asterisk with the RADIO_RELAX compile
parameter turned off, and see if you like it
that way better. I can guarantee you that you will
have less "falsing" if you do that. What I can not
guarantee is that you will get all the "real" digits
decoded reliably (if you do that).
Jim WB6NIL