How to detect a phone number from dtmf wav file?

I need to detect a phone number from wav file.I should use spectral analysis (function spectrogram is preferred).My main issue is detecting tone frequencies.

Answer 1

[Wayne King]

Please see this example:

DTMF detection

[M]

Maybe i haven't been specific enough,but it should automatically display phone number,not only to show me spectrogram so I have to decode it by knowing which freq is what number.I tried to solve this by setting all values to 0 in PSD matrix that are less than certain threshold.This way i can "see" each number,but I am not sure how to make Matlab code to read it and display it.This is what i have done so far: http://www.4shared.com/rar/lR7g1QaV/DTMF.html