> I seem to post this about every four months:
>
> Try:
>         ftp://ftp.parallaxinc.com/pub/picsrc/dtmf.asm

As far as I can tell, the code at that URL only *generates* DTMF.  I think
the question was whether it was possible to *receive* DTMF (a much harder
problem).  Another poster offered a program awhile back that could detect
long bursts of DTMF but it couldn't look for all seven tones at once and
consequently couldn't detect short DTMF tones.  The algorithm I've
produced does a real-time simultaneous detect on eight tones and every
1/60 second it produces a new "guess" as to what it heard.