{{Short description|Component of analog telephones}} thumb|upright|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 handset resides. It takes its name from old wooden wall telephones and candlestick telephones, where the mouthpiece was mounted on the telephone box and, due to sidetone considerations, the receiver 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.<ref name="Cyclo"/> When the handset is on the cradle, the telephone is said to be "on-hook", or ready for a call. When the handset is off the cradle, the telephone is said to be "off-hook", or unable to receive any (further) calls.
Pushing the switchhook briefly is termed a "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.<ref name="Cyclo">{{Cite book |url=https://www.gutenberg.org/files/15617/15617-h/15617-h.htm |title=Cyclopedia of Telephony & Telegraphy |publisher=American School of Correspondence |year=1919 |location=Chicago |page=132}}</ref>
==Invention== Several people claimed to be the first inventors of the switchhook (such as Thomas A. Watson<ref>[https://patentimages.storage.googleapis.com/37/f2/ae/ea79e2a7dae07b/US209592.pdf US Patent № 209,592. T.A.Watson. Automatic Switch or Cut-Out for Telephones. Patented Nov 5, 1878.]</ref><ref name="Watson">{{Cite book|author=Watson, Thomas A.|title=Exploring Life: The Autobiography of Thomas A. Watson|year=1926|location=New York|publisher=D Appleton and company|page=132}}</ref><ref>{{Cite web|lang=|url=https://telhistory.ru/telephone_history/inostrannye-izobretateli/priklyucheniya-tomasa-vatsona/|title=Приключения Томаса Ватсона|author=Иванов Александр|website=telhistory.ru|date=|publisher=Музей Истории Телефона}}</ref>), but Hilborne Roosevelt managed to get recognition and royalties for his invention.<ref>[https://patentimages.storage.googleapis.com/4a/d4/a5/444cbe66469188/US215837.pdf US Patent № 215,837. H.L. Roosevelt. Telephone Switch. Patented May 27, 1879.]</ref><ref name="Watson"/> The son of Edwin Holmes claimed to use that device long before their patents.<ref>{{Cite book|author=Holmes, Edwin Thomas|title=A Wonderful Fifty Years|year=2017|publisher=Andersite Press|page=72|isbn=9-781376-317312}}</ref><ref>{{Cite web|url=https://telhistory.ru/telephone_history/inostrannye-izobretateli/edvin-kholms-edwin-holmes-/|title=Эдвин Холмс (Edwin Holmes)|author=Иванов Александр|website=telhistory.ru|publisher=Музей Истории Телефона}}</ref>
==See also== * ''Off the Hook'' – A radio show * Permanent signal
==References== {{Reflist}}
Category:Telephony equipment Category:Telephony signals