Telephone | History, Definition, Invention, Uses, & Facts | Britannica

Home » How Did People Communicate Before The Telephone » Telephone | History, Definition, Invention, Uses, & Facts | Britannica

Maybe your like

Switch hook

1897 telephone
1897 telephoneNineteenth-century telephones typically contained a transmitter that had to be in an upright position for proper operation, with the receiver located in an attachment that rested on a hook when not in use. The tall profile of AT&T's desk set, such as the 1897 model shown here, led many people to call them “candlestick” phones.(more)

The switch hook connects the telephone instrument to the direct current supplied through the local loop. In early telephones the receiver was hung on a hook that operated the switch by opening and closing a metal contact. This system is still common, though the hook has been replaced by a cradle to hold the combined handset, enclosing both receiver and transmitter. In some modern electronic instruments, the mechanical operation of metal contacts has been replaced by a system of transistor relays.

Key People: Thomas Edison Alexander Graham Bell Johann Philipp Reis Thomas Augustus Watson Frank Baldwin Jewett (Show more) Related Topics: telephone box E1A handset anti-sidetone circuit switch hook ringer (Show more) On the Web: Heritage History - Alexander Graham Bell And The Invention Of The Telephone (Jan. 23, 2026) (Show more) See all related content
telephone c. 2000
telephone c. 2000Business telephone, c. 2000.(more)

When the telephone is “on hook,” contact with the local loop is broken. When it is “off hook” (i.e., when the handset is lifted from the cradle), contact is restored, and current flows through the loop. The switching office signals restoration of contact by transmitting a low-frequency “dial tone”—actually two simultaneous tones of 350 and 440 hertz.

Tag » How Did People Communicate Before The Telephone