“I listened to the Voice of America and Moscow Radio and eventually came across shipping and aircraft stations.” “I was able to find an explanation for those. Then I heard the strange voice — someone saying, ‘Papa November’ for five minutes while a snake charmer’s flute played in the background. And there was no explanation anywhere.” — Anonymous forum post

One might imagine that spies since the end of the cold war would be communicating over the interwebs, using AES-256 crypto. Probably not via SnapChat. You might be right. But not entirely. Since the Berlin Wall came down, the number of secret communiques being sprayed out over old-school shortwave radio to real-life spies has actually increased, leaving legions of hackers and radio nerds speculating about their origins and purpose.

So what kinds of messages do spies receive from their masters? No one knows – they’re perfectly encrypted, via the ancient but theoretically unbreakable one-time pad technique. In the age of Heartbleed SSL vulnerabilities and NSA backdoors into computer systems of all kinds, spy orgs have been broadcasting encrypted messages on the public airwaves for more than 50 years. But rather than cold streams of binary data, they’re transmitting the voices of little girls and old men, speaking strings of letters, numbers and random words over shortwave. Despite transmitting without discrimination to anyone with a shortwave receiver, no one has ever been able to crack a single message. Listeners who stumble into one of these stations are likely to hear something like this:

(complete playlist here)

Wilco fans will no doubt recognize the first sample in the list above – Jeff Tweedy is a big fan of number stations broadcasts, as are Melvins collaborator David Scott Stone, Boards of Canada, Synthetrix, Manu Chao, The Besnard Lakes, and Devendra Banhart.

The Iridial label’s Conet Project has been gathering recordings of these eerie transmissions for years, and has released a 5-disc collection of them – gathered from all over the world. It’s like the Harry Smith Anthology of American Folk Music for Get Smart fans.

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.

The captured sounds are almost guaranteed to leave you feeling small in the world, convinced that nefarious forces much larger than you are in constant operation. Data is gathered and people die as a result of what number stations say. A numbers station may well be broadcasting its waves through your body at this very moment.

From a fantastic 1999 Salon piece on number stations transmissions:

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 U.K.: “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.”

Lucky for your poor psyche, the entire collection is downloadable for free from Iridial. Integrated into your existing MP3 collection, these recordings make for the perfect palate cleanser between Captain & Tennille and Captain Beefheart licks.

Direct download

But beware: Some listeners complain of bizarre side-effects after extended listening sessions:

It may be just a coincidence, but I began to suffer from very strange symptoms while listening to number stations recordings for extended periods of time; dizziness, sleeping disorder (insomnia) and strange dreams/nightmares. … What does worry me is that I’ve recently begun to feel kind of very weak and shorts electric shocks through the top of my spine/neck. I don’t know what it is, and I’m not sure it is actually related to the listening of number stations recordings, but the problem appeared when I got deeply into that thing. –Anonymous forum post

Music to the ears of Boris and Natasha.

Update: Apparently there has been a spate of numbers stations posts in recent months. Coincidental?

• 99% Invisible, Episode 97: Numbers Stations
• BBC Magazine: The spooky world of the ‘numbers stations’