Telephone hook

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 something, but not the telephone from the line or the phone could not ring.

When the handset is off the cradle, the telephone is said to be "off-hook", or unable to receive any (further) calls.

Some users found that task too difficult, some forgot to turn the switch.

Several people claimed to be the first inventors of the switchhook (such as Thomas A. Watson[2][3][4]), but Hilborne Roosevelt managed to get recognition and royalties for his invention.

[5][6] The son of Edwin Holmes claimed to use that device long before their patents.