Audible ringing (ringing tone, colloquially also ringback tone) is a signaling tone in telecommunication that is heard by the originator of a telephone call while the destination terminal is alerting the receiving party. Audible ringing is typically a repeated tone that is not synchronous with the cadence of the power ringing signal that is sent to the called party.
Audible ringing is usually generated in the switching system closest to the calling party, especially when under the control of strict implementations of Signalling System No. 7 and the Customized Application of Mobile Enhanced Logic (CAMEL) signaling system. It may also be generated in the distant switch, transmitted in-band, so that in analog networks the caller could monitor the quality of the voice path of the connection before the call is established. Remote call progress indication permits customized tones or voice announcements by a distant switch in place of the ringing tone.
The ringing tone is often also called ringback tone. However, in formal telecommunication specifications, ringback has a different definition. It is a signal used to recall either an operator or a customer at the originating end of an established telephone call. It is also needed for coin-telephone lines to ring the telephone when the customer has hung up prematurely, for example to collect required overtime deposits.
Also known as caller tunes in some countries, such as South Africa, ringback music is a service offered by mobile network operators to permit subscribers to select music or even install personalized recorded sounds for audible ringing.
Coming soon – a directory of caller tunes providers in South Africa