A telephone exchange, also known as a telephone switch or central office, is a crucial component in the public switched telephone network (PSTN) or large enterprise telecommunications systems. It facilitates the interconnection of telephone subscriber lines or digital system virtual circuits, enabling telephone calls between subscribers.
A telephone operator manually connecting calls with cord pairs at a telephone switchboard
A modern central office, equipped with voice communication and broadband data capabilities
Tivadar Puskás
1922 diagram of 1877 Boston exchange
A telephone call or telephone conversation, also known as a phone call or voice call, is a connection over a telephone network between the called party and the calling party. Telephone calls started in the late 19th century. As technology has improved, a majority of telephone calls are made over a cellular network through mobile phones or over the internet with Voice over IP. Telephone calls are typically used for real-time conversation between two or more parties, especially when the parties cannot meet in person.
An early 20th century candlestick telephone used for a phone call
An early 21st century mobile phone being used for a phone call
U.S. President Gerald Ford on the phone
