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Gretacoder 103
Speech scrambler

The Gretacoder 103 was a secure telephone unit, sold by Gretag in Regensdorf (Switzerland) in the early 1980s. Contrary to most other Gretag encryption devices, the Gretacoder 103 was not manufactured by Gretag, but by Telsy in Italy. It was sold by Gretag as an OEM product.

The device was based on the principle of the voice scrambler, making it less secure than true (digital) encryption units. It offered two modes of encryption: time domain and two-dimensional scrambling. The latter uses a mixture of time domain and frequency domain scrambling.

The actual mode of encryption is determined by the cryptographic key. A total of nine keys can be preset and the rotary selector at the center of the front panel is used to select the desired key compartment. The device is inserted between the telephone set and the analogue line.
Telsy TDS-2004

The Gretacoder 103 is identical to the Telsy TDS 2004. For further information and additional photographs, e.g. of the interior, please refer to our page about the Telsy TDS 2004. The Gretacoder 103 is compatible with the Gretacoder 104, with is the military variant. It was also built by Telsy (as the TDS-2004M) with whom Gretag had a very good relationship [3].

  1. Gretag, Gretacoder 103, Voice Scrambler
    4-page full-colour brochure. Date unknown, but probably early 1980s.

  2. Gretag, Gretacoder 103
    4-page product specification. Date unknown, but probably early 1980s.

  3. Oscar Steila, Managing Director of Telsy S.p.A.
    Personal correspondence, June 2013.
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Crypto Museum. Created: Friday 21 June 2013. Last changed: Saturday, 24 February 2018 - 06:51 CET.
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