score:4
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.)