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ATF Decoder 1
Car phone traffic analyser - this page is a stub

Autotelefoon-decoder 1 (car phone decoder 1) was a software package with a complementary hardware interface for the Commodore 64 home computer, for monitoring traffic on the Dutch ATF-1 mobile telephone network, produced around 1982 by SPYTECH in Arnhem (Netherlands). The software was able to store, list and print all traffic, or to track specific telephone numbers.

ATF-1 was the very first circuit-switched public mobile telephone network in the Netherlands, launched in 1980 by the state-owned PTT (now: KPN). It was a full-duplex analogue voice system with digital signalling, operating in the 150 MHz band, with no protection against eavesdropping. Only a simple (computer) scanner was needed.

Furthermore, there was no encryption of the digital data path, not even a simple form of obscuring. When placing or receiving a call, the phone numbers were exchanged between the base station and the mobile subscriber in clear.
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Shortly after the launch of the ATF-1 network, these weaknesses were discovered by hackers, who were soon able to monitor all traffic on the network by means of a cheap home computer — in this case a Commodore 64 — that was connected to a simple computer scanner by means of a suitable hardware adapter. The package was marketed by (then) 27 year old Ronald de Groot of SPYTECH in Arnhem (Netherlands) and was available from several places including his own shop.

Although the software was officially aimed at computer enthusiasts and scanner listeners – and might even have been useful for law enforcement purposes – it was soon discovered by criminals, who made a living out of blackmailing people, based on intercepted compromising conversations.

  • Commodore 64 home computer
  • Scanner for the 150 MHz band
  • ATF-decoder software package
  • Hardware adapter (supplied with the package)
Last known addresses
    P.O. Box ???

ATF   Autotelefoon
Name for the Dutch automatically-switched analogue carphone networks, of which three generations have existed (nown as ATF-1, ATF-2 and ATF-3. Succeeded in 1994 by GSM.
GSM   Global System for Mobile Communication
KPN   Koninklijke PTT Nederland
Royal PTT of The Netherlands. This was the name of the former Dutch state-owned telecom monopolist PTT after its privatisation in 1989.
PTT   Staatsbedrijf der Posterijen, Telegrafie en Telefonie
Dutch state-owned telecommunications monopolist from 1881 until its privatisation in 1989. Responsible for the development and operation of the post, telegraph and telephone networks in the Netherlands. Also responsible for monitoring the radio spectrum and for enforcing the telecom laws.
  1. Sjak Jansen, De zakenman als James Bond
    Leidsch Dagblad, 13 February 1982, page 17 (Dutch)
     Direct download
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Crypto Museum. Created: Saturday 25 May 2019. Last changed: Tuesday, 22 August 2023 - 07:00 CET.
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