# Telephone hook

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Component of analog telephones

An early telephone manufactured in 1909, known as "Strowger". The black earpiece is seen resting on the hook.

A **telephone hook** or **switchhook** is an electrical switch which indicates when the phone is hung up, often with a lever or magnetic button inside the cradle or base where a [telephone](/source/Telephone) handset resides. It takes its name from old wooden wall telephones and [candlestick telephones](/source/Candlestick_telephone), where the mouthpiece was mounted on the telephone box and, due to [sidetone](/source/Sidetone) considerations, the [receiver](/source/Transceiver) was separate, on a cable. When the telephone was not in use, the receiver was hung on a spring-loaded hook; its weight would cause the hook to swing down and open an electrical contact, disconnecting the talking circuit from the line.[1] When the handset is on the cradle, the telephone is said to be "[on-hook](/source/On-hook)", or ready for a call. When the handset is off the cradle, the telephone is said to be "[off-hook](/source/Off-hook)", or unable to receive any (further) calls.

Pushing the switchhook briefly is termed a "[hook flash](/source/Hook_flash)".

## Purpose

Telephone switchhook separates talking and signaling circuits of the telephone so that only one is active at a time. Before the invention of the switchhook the user had to manually turn the switch. Some users forgot to turn the switch, leaving the telephone off-hook after the end of the call.[1]

## Invention

Several people claimed to be the first inventors of the switchhook (such as [Thomas A. Watson](/source/Thomas_A._Watson)[2][3][4]), but [Hilborne Roosevelt](/source/Hilborne_Roosevelt) managed to get recognition and royalties for his invention.[5][3] The son of [Edwin Holmes](/source/Edwin_Holmes_(inventor)) claimed to use that device long before their patents.[6][7]

## See also

- *[Off the Hook](/source/Off_the_Hook_(radio_program))* – A radio show

- [Permanent signal](/source/Permanent_signal)

## References

1. ^ [***a***](#cite_ref-Cyclo_1-0) [***b***](#cite_ref-Cyclo_1-1) [*Cyclopedia of Telephony & Telegraphy*](https://www.gutenberg.org/files/15617/15617-h/15617-h.htm). Chicago: American School of Correspondence. 1919. p. 132.

1. **[^](#cite_ref-2)** [US Patent № 209,592. T.A.Watson. Automatic Switch or Cut-Out for Telephones. Patented Nov 5, 1878.](https://patentimages.storage.googleapis.com/37/f2/ae/ea79e2a7dae07b/US209592.pdf)

1. ^ [***a***](#cite_ref-Watson_3-0) [***b***](#cite_ref-Watson_3-1) Watson, Thomas A. (1926). *Exploring Life: The Autobiography of Thomas A. Watson*. New York: D Appleton and company. p. 132.

1. **[^](#cite_ref-4)** Иванов Александр. ["Приключения Томаса Ватсона"](https://telhistory.ru/telephone_history/inostrannye-izobretateli/priklyucheniya-tomasa-vatsona/). *telhistory.ru*. Музей Истории Телефона.

1. **[^](#cite_ref-5)** [US Patent № 215,837. H.L. Roosevelt. Telephone Switch. Patented May 27, 1879.](https://patentimages.storage.googleapis.com/4a/d4/a5/444cbe66469188/US215837.pdf)

1. **[^](#cite_ref-6)** Holmes, Edwin Thomas (2017). *A Wonderful Fifty Years*. Andersite Press. p. 72. [ISBN](/source/ISBN_(identifier)) [9-781376-317312](https://en.wikipedia.org/wiki/Special:BookSources/9-781376-317312).

1. **[^](#cite_ref-7)** Иванов Александр. ["Эдвин Холмс (Edwin Holmes)"](https://telhistory.ru/telephone_history/inostrannye-izobretateli/edvin-kholms-edwin-holmes-/). *telhistory.ru*. Музей Истории Телефона.

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Adapted from the Wikipedia article [Telephone hook](https://en.wikipedia.org/wiki/Telephone_hook) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Telephone_hook?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.