TheCodeBreakers
like other European post offices, handled telephone and telegraph traffic
as well as mail—-realized that the only telephone link between England
and the United States was the radio circuit, and it reported "The special
national political importance of this communication connection has
caused the D.R.P. to try with all available scientific means to decipher
the conversation carried on this connection." A task force under Postal
Counselor Graduate Engineer Vetterlein of the D.R.P.'s
Forschungsanstalt ("Research Bureau") set to Work on the problem. The
engineers soon learned the nature of the A-3 system and found that they
had to wire circuits for only the six different combinations of subband
substitutions. Naturally, they had to experiment to find the exact
subband divisions and the sequence in which
I
the six. combinations were used, but from start to finish the solution
took only a few months. They completed it by September, 1941. Within a
few more months the D.R.P
annaabi.ee 
