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Siemens T-37
Electromechanical teletypewriter - this page is a stub

T. Typ 37 b, commonly abbreviated T-37, was an electromechanical teletypewriter (German: Fernschreiber), developed around 1933 by Siemens & Halske in Berlin (Germany). It is suitable for digital 5-bit telegraphy communications networks (telex), using the ITA-2 (baudot) standard.

T-37 is the success to the T-36. It was used in the years before, during and after World War II (WWII), on many telegraphy networks in Europe, in­cluding the public telex networks of Germany, Belgium, France, Austria and The Netherlands. A Dutch variant is shown in the image on the right.

During WWII, the machine was used extensively by the German Army for communication with all parts of the war theatre, mainly over fixed land-lines, but occasionally also over the air (radio). A variant of the machine with built-in One-Time Tape encryption, was known as the T-37/ICA.

In addition, the T-37 was sometimes used in combination with external OTT cipher equipment, such as the Siemens Schlüsselgerät D.

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  • 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 (OTT) 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 binary xor-ed with the letters from the plaintext. It is the automated form of the On-Time Pad (OTP) cipher. When correctly applied and used with a truly random tape, it is unbreakable [2].

Callsign generator
Callsign generator of the Siemens T-37

Callsign generator of the Siemens T-37
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Callsign generator of the Siemens T-37

The T-37 is known to have been in service in the following countries:

  • Austria
  • Belgium
  • Denmark
  • Germany
  • Netherlands
  1. Afbeeldingen Verreschrijvers Type 37 en Type 34 en Ponsontvangers
    Detailed pictures and drawings of T-37 and T-34 (Dutch).
    PTT, 1951. 3rd print.

  2. Tgf 1011a, montage-, instel- en onderhoudsvoorschrift T typ 37 g t/m i
    Installation, alignment and maintenance manual (Dutch).
    PTT, November 1956, Issue 1.

  3. Tfg 1011b, Afbeeldingen
    Pictures, belonging to Tgf 1011a (Dutch).
    PTT, November 1956, Issue 1. 1

  4. Tgf 1024a, Beschrijving bladschrijver T typ 37 a t/m i
    Description of T-37a thru i teleprinters (Dutch).
    PTT, August 1959. Issue 2. CM303981.

  5. Tgf 1024b, Afbeeldingen
    Pictures, belonging to Tgf 1024a. (Dutch).
    PTT, August 1959. Issue 2. CM303981.

  6. 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.

  7. Afregelvoorschrift voor den Verreschrijver en den Reperforator Fabr. S. & H.
    TLX 23. Alignment procedure for the Siemens T-37 (Dutch). A5 size.
    CM303970. To be used with item (F) CM303971.

  8. Afbeeldingen van den Verreschrijver en den Reperforator Fabr. S. & H.
    TLX 70. Images of the Siemens T-37 (Dutch). A4 size.
    CM303971. To be used with item (F) CM303970.

  9. Blattschreiber T typ 37 h mit Schlüsselzusatz - Manual (German)
    Fs Bs 2179/80. Si9emens & Halske, 23 May 1956. 2
  1. Document kindly provioded by Gert Stam [1].
  2. Document from MfS Abt XI 385 archive, obtained from BStU [4] and kindly provided by Jörg Drobick [5].

  1. Gert Stam, restored Siemens T-37 — THANKS !
    November 2017.

  2. Teleprinter Museum, Siemens telex machines
    Retrieved January 2018.

  3. Jerry Proc and contributors, T-37 ICA
    Retrieved January 2018.

  4. Bundesbeauftragte für die Stasi-Unterlagen (BStU) 1
    Federal Commissioner for the Stasi-Records.

  5. Jörg Drobick, Personal correspondence
    16 October 2023.
  1. Full name: Bundesbeauftragte für die Unterlagen des Staatssicherheitsdienstes der ehemaligen Deutschen Demokratischen Republik (DDR) — Federal Commissioner for the Records of the State Security Service of the former German Democratic Republic (GDR) — officially abbreviated BStU.

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Crypto Museum. Created: Monday 15 January 2018. Last changed: Tuesday, 17 October 2023 - 15:46 CET.
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