Scrambler Telephones

Discussion in 'Trux Discussion Area' started by Dave55, Aug 27, 2015.

  1. Dave55

    Dave55 Atlanta, USA

    I've seen scrambler telephones or scrambler phones referenced many times in WWII related books and papers, most recently in Bradley's "A SoldIers Story".

    I can't find much information on how they worked. I get the impression that they were not very secure. Anyone have any good information them?

  2. Trux

    Trux 21 AG Patron

    There were several types but the most common was intended only to prevent eavesdropping. In WW2 phone lines were routed through manual exchanges so a number of operators could hear conversations. It was also a simple matter to connect a handset to a line and listen in. The scrambler added meaningless signals to the speech so that it was unintelligible unless a descrambler was used to remove the additional signal. It was secure enough for most purposes.

    Secure coded teleprinters were available for secure line communications.


    PS. Of course the word came to be used as a generic term so that not all references to scramblers actually refer to the method I describe.
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  3. Trux

    Trux 21 AG Patron

    I can not find a reference now but I seem to remember that the wartime scamblers needed to have the buttons on the two handsets pressed more or less simultaneously so that the scrambler and descrambler were in sync. Hence in films the caller says scramble and then presses the button, trusting the person on the other end to do the same. Not serious if he did not since it was a fail safe operation. He simply would not be able to hear any speech, nor would anyone else though.

  4. BC610E

    BC610E Junior Member

    A Google search on "WW2 voice scramblers" turned up a mountain of info, particularly here:-

    Look also at the "Voice" tab on the sidebar, there is a lot of technical info there, below the modern equipment.

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  5. geoff501

    geoff501 Achtung Feind hört mit

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