![]() Power ringing and audible ringing are not generally synchronized. The caller is informed about the progress of the call by the audible ringing signal, often called ringback tone. In many systems, including North America Bellcore standards, Caller ID signals are sent during the silent interval between the first and second bursts of the ringing signals. Some central offices offer distinctive ring to identify one of multiple telephone numbers assigned to the same line, a pattern once widely used on party line (telephony). These patterns may vary from region to region, and other patterns are used in different countries around the world. In Australia and the UK, the standard ring cadence is 400 ms on, 200 ms off, 400 ms on, 2000 ms off. In North America, the standard ring cadence is two seconds of ringing followed by four seconds of silence. The ringing pattern is known as ring cadence, in which the high voltage ring current is switched on and off to create the pattern. The telephone exchange immediately removes the ringing signal from the line and connects the call. This signals that the telephone call has been answered. In POTS switching systems, ringing is said to be "tripped" when the impedance of the entire telephone line ( local loop) is reduced when the telephone handset is lifted off the hook. For example, ringing bursts with a shorter interval between them might be used to signal a call from a given number. ![]() Variation of the ring signal can be used to indicate characteristics of incoming calls. While the sound produced is still called a "ring", some phones electronically produce a warbling, chirping, or other sound. Mobile phones have been fully digital since the early 1990s second-generation ("2G") devices, hence are signaled to ring as part of the protocol they use to communicate with the cell base stations. Fixed phones of the late 20th century and later detect this ringing current voltage and trigger a warbling tone electronically. Originally this voltage was used to trigger an electromagnet to ring a bell installed inside the telephone, or in a nearby mounted ringer box. Typically, solid-state oscillators have replaced them. In smaller offices, special sub-cycle magnetic oscillators were used. Large central offices used motor-driven generator sets for both ringing and other signals such as dial tone and busy signals. Ringing voltage is produced by various sources. Some non- Bell Company system party lines in the US used multiple frequencies for selective ringing. In Europe it is around 60–90 VAC with a frequency of 25 Hz. 90 volts AC with a frequency of 20 hertz. ![]() The ringing signal in North America is normally specified at ca. (SLC is a trademark of Alcatel-Lucent, but is often used generically.) Telephones with electromagnetic ringers are still in widespread use. This is done at the Central Office, or a neighborhood multiplexer called a "SLC" for Subscriber Line Carrier. On a POTS interface, this signal is created by superimposing ringing voltage atop the −48 VDC already on the line. For mobile phones, the network sends a message to the recipient's device, which may activate a sound, or a visual or vibrating indication. The ringing current originally operated an electric bell. ![]() Landline telephones typically receive an electric alternating current signal, called power ringing or ringing signal, generated by the telephone exchange to which the telephone is connected. Customers can buy or generate custom ringtones for installation on the device.Ī telephone rings when the telephone network indicates an incoming call, so that the recipient is alerted of the call attempt. Originally referring to and made by the electromechanical striking of bells, the term now refers to any sound on any device alerting of a new incoming call-up to and including recordings of original telephone bells.Įlectronic telephones, especially smartphones, are manufactured with a preloaded selection of ringtones. A ringtone, ring tone or ring is the sound made by a telephone to indicate an incoming call.
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