Editing Ringdown (section)

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{{redirect|Ring Off|the song|Ring Off (song)}}
{{hatnote|For the astronomical phenomenon, see [[Binary black hole]]}}
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{{Use American English|date=September 2024}}

In [[telephony]], '''ringdown''' is a method of [[Signaling (telecommunications)|signaling]] an operator in which [[telephone]] ringing current is sent over the [[telephone line|line]] to operate a lamp or cause the operation of a self-locking [[relay]] known as a ''drop''.

Ringdown is used in manual operation, and is distinguished from automatic signaling by [[Dialling (telephony)|dialing]] a number. The signal consists of a continuous or pulsed alternating current (AC) signal transmitted over the line. It may be used with or without a [[telephone switchboard]].  The term originated in [[telephone magneto|magneto]] telephone signaling in which cranking the magneto generator, either integrated into the telephone set or housed in a connected ringer box, would not only ''ring'' its bell but also cause a drop to fall ''down'' at the [[telephone exchange]] switchboard, marked with the number of the line to which the magneto telephone instrument was connected.  At the end of the conversation, one participant would crank to ''ring off'', signaling the operator to take down the connection.  In modern British English, "ring off" still means ending a telephone conversation, though it is of course done by other means.  Ring off is also used figuratively to indicate no longer communicating with a person.

The last ringdown telephone exchange in the United States was located at [[Bryant Pond, Maine]], had 400+ subscribers, and converted to dial service in October 1983.