Who has a picture or physical description of the A3 scramble telephone system, which was used for speech privacy by Roosevelt and Churchill between 1940 and 1943. The system was most likely located near the international switchboard in the AT&T building at 27 Walker Street in New York. There seems to be no pictures left of the A3 except for a photo in the New York Times in 1940. This in sharp contrast to the first digital telephone system SIGSALY of which many photos exist. I understood that the archives of AT&T had to turn over all material on the A3 to the US authorities when the war ended.

  • I think the document is actually titled "History of speech privacy systems-1970" and apparently the AT&T Archives and History Center has (or at least had) a copy.
    – Steve Bird
    Commented May 5, 2023 at 9:47
  • @Chuck - site convention is that the question should contain everything you know/ all the research you have done. We discourage OP from adding comments. I've moved your comment into the question. Please validate that my edit helped, then flag comments for deletion where they are no longer needed. The longer the comment string, the less likely you are to get a satisfactory answer. (and welcome to the site and thank you for a couple of good questoins)
    – MCW
    Commented May 5, 2023 at 12:59
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    I presume you have found chris-intel-corner.blogspot.com/2012/02/… - further, the report (inter-departmental memorandum?) appears to be by a D. Mitchell, who may also be linked to the first AT&T mobile phone deployment in 1946.
    – Jon Custer
    Commented May 5, 2023 at 13:01
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    Frustratingly, blog.sciencemuseum.org.uk/scrambled-phones does not have an A3 picture
    – Jon Custer
    Commented May 5, 2023 at 13:10
  • I think we can rule out your West Street guess for the location, in favor of Walker Street: I have talked with Bell Labs old timers, and the division of work was such that operational systems in commercial service were run by Long Lines on their own premises, not Bell Labs on theirs. Commented May 5, 2023 at 13:39

1 Answer 1


There is a photo in the article "Diplomacy in Scrambled Words" by Hal Borland appearing in the 22 September 1940 Sunday New York Times Magazine, pp. 5,15. The picture is on p.5, and the caption reads "... an engineer adjusting scrambled sound tones". It shows a nerd hunched over a telephone equipment console.

The article states the location is in the "Overseas Control Room of the Telephone Building in New York", and gives no further street address. But it was named in Cowan's 1930 article "Transoceanic Telephone Service-Short-Wave Stations Planning and Construction of a Short-Wave Radio System" as being 24 Walker Street. (The 47 Walker Street address mentioned in the question is given by Kahn, who cites the 22 September 1940 NYT article, and a 8 October 1939 one, but neither NYT article gives a street address. I suppose "47" is Kahn's mistake.)

  • @kichi: wow fantastic find. Very good photo. It shows a rather small machine that did the scramble. I just perused the Time Machine of the NYT and found more articles (without photos) about how the scramble worked, including a reference to Walker Street (no number). It is fascinating to see that the NYT commented without any hesitation on the machine at a time when the US was not yet at war and no censor was involved.
    – user61079
    Commented May 6, 2023 at 8:20

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