There are two kinds of dedicated radio listeners. Most are those who listen regularly to their FM or AM station of choice, or to a station that only broadcasts on the internet. The rest are dedicated to other frequency scales: high frequency (also known as shortwave), followed by very high frequency and, after that, the ultra high frequency range, which includes police scanner talk and even satellite signals. Shortwave listeners encounter a world of mostly international radio stations broadcasting from countries like China, Cuba, Iran, or Romania. These frequencies also include amateur radio and marine and air traffic.
Sooner or later, however, those who listen to these more off-beat signals will stumble across strange broadcasts repeating number groups in digitally synthesized voices. Sometimes they are read live, sometimes in Morse code, and sometimes by means of digital noise transmission. These are the so-called numbers stations.
Numbers stations have been in existence since World War I. Over the years they have attracted sporadic interest from journalists, video game designers, and filmmakers. Despite this attention, there are few explanations of what these signals actually are. Too often, they are described as “spooky,” “creepy,” or “mysterious,” and the discussion stops there. It may be disappointing to some, but these stations are not signals from aliens or mind control devices, nor are they dead relics of the Cold War — rather, these stations are part of the sophisticated work of intelligence agencies and militaries, and they are very much still on the air. This article will explain what they are, how to listen to them, and why they matter.