Telephone switchboard

U.S. Air Force operator works a switchboard in the underground command post at Strategic Air Command headquarters, Offutt Air Force Base, Nebraska in 1967.

A large Bell System international switchboard in 1943

A telephone switchboard is a telecommunications system used in the public switched telephone network or in enterprises to interconnect circuits of telephones to establish telephone calls between the subscribers or users, or between other exchanges. The switchboard was an essential component of a manual telephone exchange, and was operated by one or more persons, called operators who either used electrical cords or switches to establish the connections.

单词	Manual exchange
释义	Manual exchange 英语百科 Telephone switchboard A telephone switchboard is a telecommunications system used in the public switched telephone network or in enterprises to interconnect circuits of telephones to establish telephone calls between the subscribers or users, or between other exchanges. The switchboard was an essential component of a manual telephone exchange, and was operated by one or more persons, called operators who either used electrical cords or switches to establish the connections.
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Manual exchange

Telephone switchboard