The Secret World of Number Stations

Back in the days of Cold War espionage, foreign intelligence agencies used to communicate with agents on the field via shortwave radio. Radio transmitters placed at secret locations around the world would broadcast coded messages usually in the form of an automated voice reciting a string of numbers or letters. The message often began with a melody, or a set of beeps, or a buzz, followed by the actual coded message read aloud by a voice. Anyone with a radio receiver tuned into that frequency could hear it, but only the intended recipient with proper decoding instructions could decipher the message. For the rest of the listeners, they were just a string of random numbers. Ham radio operators, who frequently stumbled upon these secretive transmissions, called them “number stations”. Photo credit: k'nash/Flickr One of the first known use of number stations was during the First World War, and one of the first civilians to discover them was Anton Habsburg, the Archduke of Austria and Prince of Tuscany, who was a young teenager at that time. Habsburg would write down the coded message from enemy stations, and on his way to school dutifully hand the piece of paper to the war office. The war office, of course, had its own listening post but once when the receiving stations at the war office couldn’t operate due to heavy frost, they used Hasburg’s copy of the message. The use of number stations rose during the Cold War era. The British Secret Intelligence Service used to operate one out of Bletchley Park in the mid-1970s, and later from RAF Akrotiri in Cyprus. Amateur radio operators called it the “Lincolnshire Poacher”, because the station used melodies from the English folk song "The Lincolnshire Poacher" as an interval signal. The former state of Czechoslovakia also used numbers stations for espionage, as acknowledged by the Czech Ministry of the Interior and the Swedish Security Service.