asterisk users - May 2004 - DTMF transmitted over IAX2 coming out as clicks at the other end

I'm having a weird problem with IAX2 in today's CVS HEAD.  I have two
boxes
with T100P cards connected via IAX2.  Calls between them work fine, but when 
I press a key at one end, it comes out the other end as a click, with no 
tone.  I've tested the DTMF on the T1 using SendDTMF with an outgoing call, 
and it sounds fine in that case; it seems to be only IAX2 that has the 
problem.  iax2 debug confirms that the digits are arriving as type DTMF, with 
the right subclass, so I'm thinking it's a problem with the way Asterisk
is
synthesizing the digits.  I've poked through the chan_iax2 code, but I
can't
find the DTMF synthesis - has anyone had this problem, or can someone point 
me towards the right place to look?

Thanks,
Mark