when touch tone dialing first came in,
i remember reading a story about how
someone had learned to by-pass the
pay phone by making free calls
using whistling .
i think those tones are made up
of multiple tones now.

have you ever seen a song book
with tunes you can play by
dialing?

you are supposed to hold down the
button on the phone so you do not
make an inadvertant international
long distance call, though.