During WWII the Soviet Union had several radio-facsimile stations. Their transmissions were intercepted by the German signal intelligence agencies OKH/GdNA Group VI and Wa Pruef 7/IV. According to postwar reports they contained ‘hand-written communications, typewritten texts, drawings, and weather maps’ and ‘technical diagrams and charts’.
This wasn’t the last time that radio-fax communications of communist countries were compromised. According to Matthew M. Aid’s ‘The secret sentry’, p142 after the USS Pueblo was captured by the North Koreans in 1968 a USAF listening post in Japan intercepted its top secret documents being transmitted on the Pyongyang-Moscow radio-facsimile link.