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STARS:Electromechanical Telephone-Switching

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Author: Sheldon Hochheiser

Citation

Originally, all telephone calls required the participation of an operator. This began to change when a crude automatic switch, invented by Almon Strowger, was improved into the first practical automatic switch around 1900. The application of Strowger switches, as well as panel, rotary, and crossbar switches, automated the telephone system. Automatic telephone switching was critical in making the telephone the influential mass market technology it became. It was also influential as an early and widespread example of automation of an electromechanical service.

Timeline

1878 The first manual telephone exchange opens in New Haven, Connecticut.
1889 Almon Strowger invents the first automatic telephone switch.
1891 Strowger receives US Patent 447918 for his invention.
1891 The Automatic Electric Co. is formed to develop a practical Strowger system.
1892 The first prototype of the Strowger system operates.
1896 Alexander Keith, John Erickson, and Charles Erickson invent the dial telephone.
1896 The first prototype of a dial telephone system operates.
1912 Gotthief A. Betulander invents the first all-relay telephone switch.
1913 John Reynolds invents the crossbar selector.
1916 William Blauvelt develops a telephone numbering plan for large cities.
1921 AT&T introduces the panel switch, designed for use in large cities.
1938 AT&T installs the first #1 crossbar switch in New York City.
1943 AT&T introduces the #4 crossbar switch, designed for long distance calls.
1948 AT&T introduces the #5 crossbar switch, designed for suburban exchanges.
1951 Customer dialing of long distance calls begins in the United States.
1965 AT&T installs the first all-electronic telephone switch.

Essay

In January 1878, less than two years after Alexander Graham Bell of Boston, Massachusetts received his first patent for the telephone, the world’s first telephone exchange entered service in New Haven, Connecticut. Each of the twenty-one subscribers could call an operator at a central switchboard, who in turn could connect the subscriber to the desired subscriber. Within a decade, such telephone exchanges, with many improvements along the way, were in operation in nearly every city in the United States. These were under license from American Bell Telephone, the holder of Bell’s patents. There was similar, but somewhat later development in most of the developed world. Every telephone call required the assistance an operator or, as exchanges began to be connected to other exchanges, multiple operators. To a substantial extent, the story of innovations in telephony is an American story, in part because as late as the 1950s, the U.S. had more than half of the world’s telephones.

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About the Author(s)

Dr. Sheldon Hochheiser is archivist and institutional historian at the IEEE History Center in New Brunswick, New Jersey. Prior to joining IEEE, he spent sixteen years as corporate historian for AT&T, acting as both subject matter expert on AT&T history and manager of the corporate archives. While at AT&T, he curated historical exhibits, completed oral histories with company executives, and studied every aspect of the history of the telephone in the United States. He earned a Ph.D. in the History of Science at the University of Wisconsin, and a B.A. in Chemistry-History at Reed College.