Simple demo of 'tone dial' technique. Click the buttons to make some good old telephone sounds! Whenever you click a button (or press it on your keyboard), you will: ‣ hear its DTMF tone, ‣ see the audible frequencies flash up in red. WARNING The sound generated by this project, when picked up by the open receiver of a telephone, may actually dial a phone number. This can be a fun experiment, but please be careful whose number you dial.
