Numbers Station

Numbers stations are shortwave radio stations of uncertain origin. They generally broadcast artificially generated voices reading streams of numbers, words, letters (sometimes using a spelling alphabet), tunes or Morse code. They are in a wide variety of languages and the voices are usually female, though sometimes male or children's voices are used.

Evidence supports popular assumptions that the broadcasts are used to send messages to spies. This usage has not been publicly acknowledged by any government that may operate a numbers station, but in 2001, the United States tried the the Cuban Five with spying for Cuba. The group had received and decoded messages that had been broadcast from a Cuban numbers station. In June 2009, the United States similarly charged Walter Kendall Myers with conspiracy to spy for Cuba and receiving and decoding messages broadcast from a numbers station operated by the Cuban Intelligence Service to further that conspiracy.

It has been reported that the United States uses numbers stations to communicate encoded information to persons in other countries.

Numbers stations appear and disappear over time (although some follow regular schedules), and their overall activity has increased slightly since the early 1990s. This increase suggests that, as spy-related phenomena, they were not unique to the Cold War.

Numbers stations are often given nicknames by enthusiasts, often reflecting some distinctive element of the station such as their interval signal. For example, the "Lincolnshire Poacher", formerly one of the best known numbers stations (generally thought to be run by MI6 as its transmissions have been traced to RAF Akrotiri in Cyprus), played the first two bars of the folk song "The Lincolnshire Poacher" before each string of numbers. "Magnetic Fields" plays music from French electronic musician Jean Michel Jarre before and after each set of numbers. The "Atención" station begins its transmission with the Spanish word "¡Atención!"

Although it is time-consuming and may require costly global travel to pinpoint the source of a radio transmission in the shortwave band, errors at the transmission site, radio direction-finding, and a knowledge of shortwave radio propagation have provided armchair detectives clues to some number station locations.