Does anyone know how to play sound files (any kind ie. wav / mp3 etc...) or even just simple tones (multiple tones simultaneously or consecutively)?

I'm making a ringtone editor for polyphonic mobiles (so I can immortalise things like Bay City Rollers, Bucks Fizz and Bananarama tunes so you can play them endlessly to your friends). And I need a preview facility before uploading to the phone.