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. A telephone rings when the telephone network indicates an incoming call, so that the recipient is alerted of the call attempt.
0 kommentar(er)
