The standard 'downloadable' ringtones that Nokia developed back in 1998 can only play one note at a time and no more. It is possible to make the older ringtones sound like more than one note is being played even though only one note is actually being played. Polytones allow more than one note to be played at once and also increase the sounds that are available to be played by using the SP-MIDI format. This will increase the range of music that will now be able to be created as a ringtone. Polyphonic Ringtone compatible mobile phones are fast replacing older mono ringtone phones. The following mobile phones are compatible.

Surce: http://www.polyphonic-ringtones-ring-tones.co.uk