Audacity
From Osnow
How to Use Audacity to decode DTMFs (manually)
- Goto Wikipedia's page on DTMF, scroll down so you can see the Tone Freq Matrix (chart) in the background
- Open the sound file in Audacity
- select JUST the DTMF sound (no extra noise to muddy the sample)
- click Analyze, select Frequency analysis
- Hover your mouse over each peak to see the frequency.
As you mouse over the frequencies in the display, Audacity will show you the exact frequency of the spike. It takes two spikes to make a DTMF, being Dual Tone and all. :)
Simply lookup the matching row and column of the two spikes and ouila! you have your DTMF. When I did it it looked something like this...
