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The telephone played a major communications role in American history from the 1876 publication of its first patent by Alexander Graham Bell onward. In the 20th century the American Telephone and Telegraph Company (AT&T) dominated the telecommunication market as the at times largest company in the world, until it was broken up in 1982 and replaced by a system of competitors.
Telephone numbers listed in 1920 in New York City having three-letter exchange prefixes. In the United States, the most-populous cities, such as New York City, Philadelphia, Boston, and Chicago, initially implemented dial service with telephone numbers consisting of three letters and four digits (3L-4N) according to a system developed by W. G. Blauvelt of AT&T in 1917. [1]
Most automatic dial switching systems were designed since the early 1920s to provide service for as many as ten-thousand subscriber lines. Each of these switching systems constituted a local telephone exchange, formally known as a central office. Therefore, each telephone connected to a central office had a unique four-digit line or station number.
As phone lines became more popular—between 1942 and 1962, the number of phones in the U.S. grew 230% to 76 million—telephone companies realized they would run out of phone numbers.
The master telephone patent granted to Bell, 174465, March 7, 1876. The modern telephone is the result of the work of many people. [12] Alexander Graham Bell was, however, the first to patent the telephone, as an "apparatus for transmitting vocal or other sounds telegraphically".
1 November 1960: The Bell System begins testing its push-button phone, starting with service in Findlay, Ohio. [39] 1960: Bell Labs conducts extensive field trial of an electronic central office in Morris, Illinois, known at the Morris System. 1960s: Bell Labs developed the electronics for cellular phones; 1961: Initiation of Touch-Tone service ...
By the early 1960s, DDD had become commonplace in cities and most towns in the United States and Canada. By 1967, the number of assigned area codes had grown to 129. [7] The status of the network of the 1960s was reflected by a new name used in technical documentation: North American Integrated Network. [7]
Telephone service for dispatchers and service personnel between way stations along railways used a form of party line service for many decades starting in the early 1900s. Railroad telephone systems often consisted of several dozen way stations interconnected with a shared line that used DC voltages as high as 400 V for selective signaling to ...