is the sound made by a telephone to indicate an incoming call. The term, however, is most often used to refer to the customizable sounds available on mobile phones. This facility was originally provided so that people would be able to determine when their phone was ringing when in the company of other mobile phone owners.
A phone only rings when a special "ringing signal" is sent to it. For regular telephones, the ringing signal is a 90-volt, 20-hertz, AC wave generated by the switch to which the telephone is connected. For mobile phones, the ringing signal is a specific, radio-frequency signal.
The first commercial mobile ring tones were created and delivered in Finland in 1998 when a Finnish mobile operator Radiolinja (today Elisa) started their downloadable mobile ring tone service called Harmonium invented by Vesa-Matti Paananen. The Harmonium contained both tools for general public to create monophonic ring tones and a mechanism to deliver them over-the-air (OTA) via SMS to a mobile handset and to bill customer on their phone bill. The service concept spread quickly in Europe and Asia and developed to be a multi billion industry globally. A ring tone service was one of the very first successful m-commerce services and contained also social media aspects like composing, sharing and rating ring tones. The Harmonium also created quickly a need for high quality professional ring tones and commercial ring tone libraries.
