Ringing voltage

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When ringing voltage (also known as ringing current , reputation or ringing hereinafter) in the telecommunications the electric voltage referred to in analog telephone lines and analog extensions of PBXs to call signaling is an incoming call at the called subscriber.

In the public telephone network in Germany, the ringing voltage is an alternating voltage of 60  V with a frequency of 25  Hz . It is generated by the ringing tone generator. Ringer generators today are electronic inverters ; Special integrated circuits are available for their control (for example the UCC2750 circuit), which generate the country-specific ringing tone frequencies from a direct voltage of mostly 48 V.

The ringing voltage is generated in the switching device ( switching center , telephone system), previously by the calling and signaling machine . In telephones with local battery technology (colloquial term crank telephone ), the crank inductor is used to generate ringing voltage.

In packet-transmitting telephony, VoIP, the call tone is simulated via the SIP protocol using the SIP command "183 Session Progress" and the "Early Media" protocol. The sending end device must signal the call to the caller.


  • Volker Jung, Hans-Jürgen Warnecke (Hrsg.): Handbook for telecommunications. Springer Verlag, Berlin / Heidelberg 1998, ISBN 978-3-642-97703-9 .
  • Hans Kurt Ibing: look into the telecommunications system. Staufen Verlag, 1949.
  • Peter R. Gerke: New Communication Networks. Springer Verlag, Berlin / Heidelberg 1982, ISBN 978-3-642-93207-6 .

See also

Individual evidence

  1. 1 TR 110-1; Technical description of the analog dial-up connections on the T-Net / ISDN of the T-Com; August 2007
  2. RFC 3960 description of the process