The German Stasi Sprach machine was used to send coded messages through numbers stations by automated voice and could also be used to send numbers in Morse code. It was used primarily by East Germany (DDR), Russia, and Cuba.
The language and specific voice can be changed by swapping out the circuit board with the EEPROMS on it through the back of it (shown in video). Also, there are settings on the machine that can be used to adjust the pitch of the voice and the speed. The sequence of numbers was programed ahead of time before sending to the agent. The Sprach machine is also capable of using One Time Tape, which feeds through the machine to program numbers into it.
This is rare equipment to come by, luckily there are collectors who intend to preserve them. The video series “Numbers Stations Revealed” by Peter Staal shows the machine reading numbers, and also uses different languages and voice settings. The machine(s) from the videos belong to a German Collector.
All of the stations that used it are now inactive, although G06 still uses the same voice, here are their ID’s and variants:
V02 (Spanish Circuit), G02, G02a, G03, G04, G06, G06a, G07, G07a, G08, G08a, G08b, G21