CRBT is the music that the caller's receiver rings when you call someone or someone calls you, that is, when you don't answer. Its function is to let the caller enjoy music, thus reducing the boring time of waiting to answer the phone. Ringtone refers to the music that someone calls you and your mobile phone rings.

CRBT (Color Ring Back Tone) is the abbreviation of "Personalized Multicolored Ring Back Tone Service", which is a service that called customers set special sound effects (music, songs, story lines, conversations between people) for other calling customers who call their mobile phones. Ringtone is the sound that a mobile phone makes when it is called. There are usually three kinds of ringtones: real ringtones, special effects ringtones and funny ringtones. The formats are MP3, waw, mmf, midi, etc. With the support of mobile phone manufacturers, different types of contacts can set different ringtones for them to distinguish.