SexualMoose:
So, I took a look and it works beautifully. Their are 2 things I have questions about though. The tone length is very strict. If the tone is too short it wont work and if it plays too long it will put print the number multiple times. Is their any chance you could make it modifiable? Also, the goertzel algorithm is supposed to compensate for magnitude on its own. Is there anyway to account for that?Again, great job and thanks for your help!
Moose
I believe the official (original ATT specs?) DTMF specs for minimum recognition time (shortest tone period) for a valid digit is around 40 msec if I recall correctly. Decoding multiple repeated digits for a single tone of any length sounds like just a 'feature' of the library. 