A numbers station is a type of shortwave radio station characterized by unusual broadcasts, reading out lists of numbers or incomprehensible coded messages. The voices are often created by speech synthesisand are transmitted in a wide variety of languages. The voices are usually female, although sometimes men’s or children’s voices are used. Some voices are synthesized and created by machines; however, some stations used to have live readers. Many numbers stations went off the air due to the end of the Cold War in 1989, but many still operate and some have even continued operations but changed schedules and operators.
The first known use of numbers stations was during World War I, and the first possible listener was Anton Habsburg of Austria. The numbers were transmitted in Morse. The Czech Ministry of Interior and theSwedish Security Service have both acknowledged the use of numbers stations by Czechoslovakia for espionage, with declassified documents proving the same. With a few exceptions, no QSL responses have been received from numbers stations by shortwave listeners who sent reception reports to said stations, which is the expected behavior of a non-clandestine station.
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