[Asterisk-Users] Problem with double-detection of DTMF tones

[Malcolm Taylor]

I'm using a current version of CVS-HEAD and am having an interesting problem
with a key user of a simple IVR application.  He's dialing into the system
from the PSTN via a TDM400P.

The application (written in php with phpagi) plays a prompt, which can be
interrupted at any time, asking for a user ID followed by the # key.  This
user's ID is 1 (he's the boss!), but when he has his telephone headset
turned on and enters his ID while the prompt is still playing, the system
interprets it as 11 about 50% of the time.  We've tested from his phone and
the only time we appear to get this double DTMF issue is while the headset
is on and he interrupts the initial prompt.  His phone without the headset
on behaves correctly, as do all other phones we've tested with.

Can anyone point me in the direction of which asterisk/zaptel parameters I
might tweak to resolve this issue?  Any advice would be greatly appreciated.

Malcolm