Types of ring tones of Mobile Phones: Monophonic: A monophonic ring tone is simply a series of musical notes, one note at a time. Polyphonic: A polyphonic ring tone can consist of several notes at a time. The first polyphonic ring tones used sequenced recording methods such as MIDI. Such recordings specify what synthetic instrument should play a note at a given time, and the actual instrument sound is dependent upon the playback device. Later, synthesized instruments could be included along with the composition data, which allowed for more varied sounds beyond the built-in sound bank of each phone. Truetone: A truetone (also known as "realtone", "mastertone", "superphonic ringtone" or "audio recording") is simply an audio recording, typically in a common format such as MP3 or AAC. Truetones, which are often excerpts from songs, have become popular as ring tones. The first truetone service was started by au on December 2002. "My Gift to You" by Chemistry was the first song to be distributed as a truetone. Sing tone: A "sing tone" is a ring tone created in karaoke style, combining a user’s recorded voice (adjusted to be both in time and in tune) with a backing track. Video Ringtone: A video ringtone is a piece of video content used as a ringtone (typically on 3G phones). Any video may be used, but usually music video excerpts are used. The best examples of these use sound and video track that loops seamlessly. It is possible to use personalised video ringtones against contacts in the phone to provide video and audio Caller Identification.