According to the information presented so far there is no doubt that the Germans could intercept the multi-channel traffic.But could they read it ?
It’s important to remember that Bamford mentions plaintext.Praun on the other hand said: ‘’ the Russians used the same cryptosystems as in the field for sending important military messages over these circuits’’.I assume he means the standard 2-part codebooks used by armed forces and NKVD.The Army High Command Signal Intelligence Agency had significant success against those systems so the traffic could definitely be read.
Another thing to consider is that the Germans didn’t waste resources on systems they considered to be too hard to break. Taking into consideration all of the above I had to assume that they wouldn’t go through the trouble of intercepting this traffic if they couldn’t actually read it. Therefore i assumed that the Soviet system was not automatically enciphered since that would mean that most/all of that traffic would be secure against the German services.
Regarding the Staats facility I hypothesized that it was the main facility where the multichannel equipment was used by the Army Ordnance Office (mainly based on the information from Praun).
Now let’s take a look at a report I found and see if it backs me up :
TICOM I-131 ‘’Special intercept activities carried on by Wa Pruf 7’’
Experiments were already in progress in 1937, with the object of intercepting Baudot and Multiplex traffic. The experiments concentrated on intercepting Russian multi-channel WT teleprinter traffic (of 8 or 15 channels). The traffic intercepted was transmitted in clear and only enciphered technically, i.e. by scrambling various channels together. With the separation of the channels the traffic was picked up in clear.
In 1938 Wa Pruf 7 organised a lecture for heads of army intercept coys in which developments in this special field were discussed. The equipment shown was very delicate and had-not yet reached its final stage of development. However, progress was so advanced that the army intercept coys were ordered to watch all special traffic they picked up, to record it on magnetophones and to forward the results to Wa Pruf 7 for analysis. In order to assist the army intercept coys in recognising special transmissions, acoustic tone films were issued. From that time onwards Wa Pruf 7 became very secretive and although it received traffic from the army intercept coys, it never reported what progress had been achieved. PW knows, however, that considerable successes were achieved during the war, especially against RUSSIA, and that before the war the Baudot link PARIS/MOSCOW had been satisfactorily, intercepted. PW has the impression that the work at STAATS was highly successful because in 1941, despite the manpower shortage, the establishment was increased.Interesting isn’t it ?
So it seems that the multichannel radio teletype traffic was indeed plaintext and it’s security rested on the splitting of the channels.During the war I assume the Soviets used it to send both plaintext and encoded messages.However once the Germans mastered the interception technique and built the fish machine it must have provided them with huge amounts of sensitive traffic.
So far I had to make a lot of assumptions but it seems I am in the right .