- Dual Tone Multi Frequency. The signal generated when you press the touch keys on a regular phone
One Sunday when I was extremely bored (perhaps I had a hangover, I don't remember) I wrote a PHP script that generates audio files containing DTMF signals for a given phone number.
Using this generator I can enter a number on my computer, pick up my phone, hold the receiver towards my computer speaker, and play the generated sound file through my computer's sound card. My phone will then be connected to the number specified. Funny the first couple of times, but otherwise almost completely useless (or did I forget something?).
I think it works in most parts of the world - correct me if I'm wrong.
It is possible to enter "spelled" phone numbers like 1-800-FOO-BAAR.
Using the query string it is possible to modify a number of parameters. These are documented in the source.
While not preparing for an exam that I have tomorrow, I rewrote the generator. Previosly it had the tones stored in files, now it generates the tones on the fly. Oh joy - "and the crowd went absolutely bananas".