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Telephone Manufacturing Company - this page is a stub

The Telephone Manufacturing Company Lrd. (TMC) was a British manufacturer of telephone equipment, founded in 1912 by Frederick Jackson, a former employee of The Private Telehone Company (PTC, London) and Intercommunicating Telephones. The company was located in London and Orpington (Kent, UK), and was small compared to its contemporary competitors.

One of the TMC logos

During WWII, the company manufactured equipment for the General Post Office (GPO), including parts for Churchill's Scrambler Phone — a speech invertor or scrambler known as the Frequency Changer. After the war, TMC marketed the Frequency Changer under the name Secraphone.

GPO series 300 telephones
British WWII scrambler phone (also known as Frequency Changer or Secraphone)
Frequency Changer No. 6AC (1944)
Simplified 232-style telephone TMC-232X for use with Frequency Changer
Product codes
  1. GB531318, Improvements in and relating to Electric Communications Systems
    28 June 1939.

  2. GB536945, Improvements in Telephone Systems
    28 November 1939.

  3. GB540089, Improvements in and relating to Electrical Communications Systems
    27 March 1940.

  4. GB549002, Improvements in and relating to Electrical Communications Systems
    30 January 1941.

  5. GB656611, Improvements in and relating to Telephone Aparatus
    17 February 1948.

  6. GB912250, Improvements in and relating to Electrical Aparatus
    8 April 1961.

  7. GB980140, Improvements in and relating to Secrecy Systems
    18 June 1962.
Known addresses
  • Telephone Manufacturing Co. Ltd.
    West Dulwich
    London, SE-21
    England (UK)
    Phone: GIPsy Hil 2211

  • Telephone Manufacturing Co. Ltd.
    St. Mary Cray
    Orpington, Kent
    England (UK)
    Phone: ORPinton 2650
  1. Robert Freshwater, The Telephone Manufacturing Company of Britain
    Website: Bob's Old Phones. Retrieved May 2021.
Further information
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Crypto Museum. Created: Thursday 27 May 2021. Last changed: Sunday, 06 June 2021 - 13:04 CET.
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