A ringtone or ring tone is the sound made by a telephone to indicate an incoming call or text message. Not literally a tone, the term is most often used today to refer to customizable sounds used on mobile phones.

A phone “rings” when its network indicates an incoming call and the phone thus alerts the user. For landline telephones, the call signal can be an electric current generated by the switch to which the telephone is connected. For mobile phones, the network sends the phone a message indicating an incoming call.

A ringtone maker allows a user to take a song from their personal music collection, select whatever section they like and send the file to their mobile phone. Files can be sent to the mobile phone by direct connection.

The fact that consumers are willing to pay up to $3 for ringtones have made "mobile music" a particularly profitable part of the music industry. Estimates vary: the Manhattan-based marketing and consulting firm Consect estimated ringtones generated $4 billion in worldwide sales. According to Fortune magazine, ring tones generated more than $2 billion in worldwide sales during 2005. In 2009, the research firm SNL Kagan estimated that sales of ringtones in the United States peaked at $714 million in 2007. SNL Kagan estimated U.S. sales in 2008 declined to $541 million, due in part to consumers having learned how to create their own ringtones.

Types of ringtones

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 ringtones 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.