dynamically generating ringtones based on the calling phone number

[Thomas Gstädtner]

For my small tool epiano (which I haven't worked on in a while
unfortunately), I use fluidsynth.
You can easily use any soundfont you want and map a tone sequence to
it, it's absolutely trivial and nice.

If you plan to do this, use fluidsynth.
You can have it run in background and play your melody in realtime
with hardly any delay.
It also has a nice API, so working with it is easy.