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  2. Telephone exchange names - Wikipedia

    en.wikipedia.org/wiki/Telephone_exchange_names

    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]

  3. Telephone exchange - Wikipedia

    en.wikipedia.org/wiki/Telephone_exchange

    Telephone exchange. 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. A telephone exchange, also known as a telephone switch or central office, is a crucial component in the public switched telephone network (PSTN ...

  4. Telephone prefix - Wikipedia

    en.wikipedia.org/wiki/Telephone_prefix

    Telephone prefix. A telephone prefix is the first set of digits after the country, and area codes of a telephone number. In the North American Numbering Plan countries (country code 1), it is the first three digits of a seven-digit local phone number, the second three digits of the 3-3-4 scheme. In other countries, both the prefix and the ...

  5. Toll-free telephone numbers in the North American Numbering ...

    en.wikipedia.org/wiki/Toll-free_telephone...

    Toll-free telephone numbers in the North American Numbering Plan have the area code prefix 800, 833, 844, 855, 866, 877, and 888. Additionally, area codes 822, 880 through 887, and 889 are reserved for toll-free use in the future. 811 is excluded because it is a special dialing code in the group NXX for various other purposes.

  6. History of the telephone - Wikipedia

    en.wikipedia.org/wiki/History_of_the_telephone

    Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876. Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois. Tivadar Puskás proposed the telephone switchboard exchange in 1876. Thomas Edison invented the carbon microphone which produced a strong telephone ...

  7. Area code 603 - Wikipedia

    en.wikipedia.org/wiki/Area_code_603

    Area code 603. Area code 603 in a 1956 map, covering the . Area code 603 is the sole area code for the U.S. state of New Hampshire in the North American Numbering Plan (NANP). It was created as one of the original 86 numbering plan areas in October 1947. In 2011, area code 603 was said to be nearing exhaustion and a second area code for New ...

  8. Public switched telephone network - Wikipedia

    en.wikipedia.org/wiki/Public_switched_telephone...

    Public switched telephone network. The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists of telephone lines, fiber-optic cables, microwave transmission ...

  9. List of telephone exchanges in London - Wikipedia

    en.wikipedia.org/wiki/List_of_telephone...

    London manual exchanges were gradually converted to Director automatic exchanges from 1927. Holborn was the first, at midnight on Saturday 12 November, a local and tandem exchange. Bishopgate and Sloane exchanges followed in six weeks, then Western and Monument exchanges. The London area contained 80 exchanges, and full conversion was to take ...