When you key in a telephone number, why does each number have a specific tone? I wondered this a couple of days ago.
Answer: http://en.wikipedia.org/wiki/Dual-tone_multi-frequency
Why do telephone numbers make certain sounds?
When you key in a telephone number, why does each number have a specific tone? I wondered this a couple of days ago.
Answer: http://en.wikipedia.org/wiki/Dual-tone_multi-frequency