The Signals Intelligence Service (SIS) was the Army's codebreaking division. It was a part of the Signal Corps so secret that outside the office of the Chief Signal officer, it did not officially exist. William Friedman began the division with three "junior cryptanalysts" in April of 1930. Their names were Frank Rowlett, Abraham Sinkov, and Solomon Kullback. Before this, all three of them had been mathematics teachers with no cryptanalysis background. Besides breaking foreign codes, they were responsible for just about anything to do with the War Department's code systems. The SIS initially worked on an extremely limited budget, lacking the equipment it needed to even intercept messages to practice decrypting.