Tones aren't right. Arithmetic is wrong.

[ClydeHoadley]

Your DTMF tones don't sound like they're working right. The tones are going down in frequency as the numbers on the keypad get bigger. The sounds for the number #9 should be higher in frequency than #1, but your program is producing a lower frequency for #9 than for #1. Compare the sounds of the keypad on your cell phone to the sounds produced by your program to see what I mean.

It appears that you've gotten your arithmetic wrong. The arithmetic should look like this:

array.array('f', ((math.sin(2.0math.piitone[0]/sr) + math.sin(2.0math.piitone[1]/sr)) for i in range(int(sr*length)) )).tostring()