Telephone hook
Component of analog telephones
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. 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".
01Purpose
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.
02Invention
Several people claimed to be the first inventors of the switchhook (such as Thomas A. Watson), but Hilborne Roosevelt managed to get recognition and royalties for his invention. The son of Edwin Holmes claimed to use that device long before their patents.
Sources and credits
This article is adapted from the Wikipedia article “Telephone hook”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Wolfsonian-FIU Museum - IMG 8151.JPG by Daderot, Public domain
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