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Siemens T-37
Fernschreiber T-37 - under construction

T. Typ 37 b, commonly abbreviated to T-37, is a teletypewriter (German: Fernschreiber), developed around 1933 by Siemens & Halske in Berlin (Germany), for use on digital 5-level telegraphy communications networks (telex), using the ITA-2 (baudot) data standard.


  • T-37
    This is the standard version of the T-37 teletypewriter.

  • T-37 ICA
    This is a special version that has been coverted for use as a One-Time Tape cipher machine. It features two large lamps on the front cover (a green one and a red one) and has a connection for an external tape reader.
T-37 ICA
The T-37 was also available as a One-Time Tape cipher machine, or Mixer. This version is known as T-37 ICA and can be recognised by two large lamps on its cover: a green one and a red one. Furthermore, it has a connection for an external paper tape reader, of which the characters are mixed on-the-fly with the letters from the plaintext. It is the automated form of the On-Time Pad cipher. When used with the truly random tape, and correctly applied, this cipher is unbreakable. [2].

  1. De Verreschrijvers T-37/LP, T-68/LP
    Description and operating instructions for the Siemens T-37 and T-68 (Dutch).
    Belgian Army. March 1967.
  1. Teleprinter Museum, Siemens telex machines
    Retrieved January 2018.

  2. Jerry Proc and contributors, T-38 ICA
    Retrieved January 2018.
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Crypto Museum. Created: Monday 15 January 2018. Last changed: Monday, 15 January 2018 - 19:58 CET.
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