What format are ringtone files on the iPhone?

iPhone ringtones can be customized easily thanks to iTunes, but what file format does Apple actually use to store ringtones? Aside from the file extension, iOS ringtones are the same as .m4a files.

Ringtones are stored using the MPEG-4 file format, with an extension .m4r. The default audio encoding for iPhone ringtones is AAC (Advanced Audio Coding) supported from 8 to 320 Kbps. These files can be played by many applications including iTunes, QuickTime, and Windows Media Player.

iPhone ringtones are also known as truetones, since they consist of music or audio recordings.