How does a ringtone work?

A ringtone relies on the computing power of the mobile phone. The common ringtone is actually programmed through a language called Ringing Tone Text Transfer Language (RTTTL) format, developed by Nokia.

Different mobile phones use different systems for encoding ringtones on their devices but most are delivered directly to your phone as part of an SMS system.

mobile-entertainment-guide provides quite a good guide to the different types of phones.