Shortwave Numbers Stations are a perfect method of anonymous, one way communication. Spies located anywhere in the world can be communicated to by their masters via small, locally available, and unmodified Shortwave receivers. The encryption system used by Numbers Stations, known as a “one time pad” is unbreakable. Combine this with the fact that it is almost impossible to track down the message recipients once they are inserted into the enemy country, it becomes clear just how powerful the Numbers Station system is.

These stations use very rigid schedules, and transmit in many different languages, employing male and female voices repeating strings of numbers or phonetic letters day and night, all year round. The voices are of varying pitches and intonation; there is even a German station (The Swedish Rhapsody) that transmits a female child’s voice!

One might think that these espionage activities should have wound down considerably since the official “end of the cold war”, but nothing could be further from the truth. Numbers Stations (and by inference, spies) are as busy as ever, with many new and bizarre stations appearing since the fall of the Berlin wall.

Why is it that in over 30 years, the phenomenon of Numbers Stations has gone almost totally unreported? What are the agencies behind the Numbers Stations, and why are the eastern European stations still on the air? Why does the Czech republic operate a Numbers Station 24 hours a day? How is it that Numbers Stations are allowed to interfere with essential radio services like air traffic control and shipping without having to answer to anybody? Why does the “Swedish Rhapsody” Numbers Station use a small girls voice?

The rerelease of the Irdial set contains one new element: a postcard that will allow you to take part in what is being called “The Conet Project: Six Degrees of Separation.” As the Conet Project people explain on the Irdial page: “We are using these cards to attempt to track down the staff that operated Numbers Stations in the past, wherever in the world they are now living. … Hopefully the people that we are able to locate (and that are willing to divulge their secrets to us) will have kept a private, detailed record of what they did, the decisions that were made, who made them, why, and everything else we are keen to know.” [Cue the X-Files theme.]

NPR did a short segment about the Irdial rerelease in November. You can listen to it online.

The rerelease is apparently only for sale via Amazon UK.

If you’re not the sort of obsessive who likes to own copies of these sorts of things—and in this case, I’m not—you can listen to dozens of numbers station recordings here.