I dont think it can be done :spangled: MP3 is an audio signal whilst MIDI is a digital control signal. Might be wrong though
there are auto converters, but they dont tend to do it very well. generally speaking there's too much going on in an mp3 to be converted to midi without sounding shit. if you want a midi of something (as you say - for ringtone purposes) you are best off doing it from scratch or hoping someone else has done it
as above i wouldnt bother as it sounds crap. search on the net @ midifarm.com or somewhere similar for ya tune.
midi is a digital signal, not an audio one like mp3. converters are utter shite. only real way to convert the notes by ear in a music production program and export as midi