July 24th, 2008 DTMF decoder
The DTMF decoder can be powered from a 9V battery or from your parallel printer port. It can detect and display all 16 DTMF digits on your computer screen in real-time. The Window’s program can be placed in the minimize mode and still detect tones while you use your computer to do other things.
DTMF decoder: [Link]
also read about the DTMF Generator.
