Twisting the dial of your shortwave radio, you come across the most "experimental" sounding station you've ever heard. A glockenspiel tune is followed by the voice of a little girl speaking numbers and letters in what sounds like a random order. Performance art? No, the message inside the madness just wasn't meant for you. Perhaps its intended for the ears of a CIA agent. Or KGB. Or MOSSAD. You've stumbled across a Numbers Station.

"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," reads the Web site of The Conet Project, an outfit that's compiled 150 Numbers Stations recordings from the last three decades on a four CD set. (The word "Conet" is the sign-off signal on one station.)

Is this spy stuff true or not? Well, a rare mainstream media article about Numbers Stations published in the Daily Telegraph last year quoted a spokesman for the Department of Trade and Industry, responsible for regulating the airwaves in the UK: "These (Numbers Stations) are what you suppose they are. People shouldn't be mystified by them. They are not for, shall we say, public consumption."

According to The Conet Project, Numbers Stations have been on the air for at least thirty years. In the early days, rather than use numbers, messages were given in secret coded sentences at the end of newscasts.

"Announcers were sometimes heard saying, 'For the benefit of our friends overseas: Peter has painted his fence red. I repeat, Peter has Painted his fence red'," the site reads.

Indeed, Numbers enthusiasts claim that periodically spies have been caught red-handed transcribing instructions from the Stations. Since the Intelligence community hasn't, and isn't likely to, come clean on the Stations, they remain an extremely entertaining curiosity. And the beauty is that anyone can tune in. They transmit on rigid schedules and can be heard all over the world, with nothing more than an inexpensive shortwave radio.

Hundreds of stations have been identified by numbers-hunters like those in ENIGMA (European Numbers Information Gathering and Monitoring Association), who publish a 'zine tracking the transmissions. Some stations begin and end their broadcasts with dissonant electronic tones, weirder than any minimalist electronica spun today; another, known as the Lincolnshire Poacher, uses obviously synthesized intonation, perhaps to make the stream of numbers sound less boring.

Still, it seems odd that the high-tech spooks haven't come up with a more modern method of communication. Then again though, radio is ideal for one-way transmissions since it's impossible to identify who's listening.

"Spies can't use any form of wired communication because a wire has two ends, and from that, 'the enemy' can know that you are receiving communications on a regular basis," according to Konet.

Tune in.

David Pescovitz (david@pesco.net) is the co-author of Reality Check (HardWired, 1996) and a contributing editor to Wired and ID Magazine.