From ARRL (source)
Secretive “Numbers Stations” Persist on HF
For many years, unidentified radio broadcasts have been transmitting coded messages, using numbers, such as “6-7-9-2-6. 5-6-9-9-0.” Even today, tuning across the HF spectrum typically will yield a “numbers station,” a mechanical-sounding voice (male or female) methodically announcing groups of single-digit numbers for minutes on end. According to Radio World, you may have tuned into a spy agency’s numbers station transmitting coded instructions to their minions worldwide. Shades of “The Americans” TV spy drama, where characters routinely receive coded messages via radio.
Numbers station transmissions typically consist of a voice “reading out strings of seemingly random numbers,” explained Lewis Bush, author of Shadows of the State, a new history of numbers stations. “These are sometimes accompanied by music, tones or other sound effects,” he said. Paul Beaumont, an associate editor of Eye Spy Intelligence Magazine, a publication dedicated to espionage and intelligence, is quoted in the Radio World article as saying, “Voice (numbers) stations are known to be spy messages.”
The article said that one of the best-known numbers stations was “The Lincolnshire Poacher,” so called due to its use of “The Lincolnshire Poacher” folk song played on a pipe organ as an identifier. Radio amateurs used direction-finding equipment to pin down the station’s eventual location to an RAF base on Cyprus, the article said.
Submitted by KD4WX