This episode was written and produced by Olivia Rosenman.

Since World War I, countries around the world have been broadcasting mysterious numerical messages via shortwave radio. Though concrete evidence is hard to come by, the general consensus is that these coded messages are meant for undercover agents operating abroad. And one particular Russian station may have an even more sinister purpose. Featuring computer engineer Andrus Aaslaid, historian Maris Goldmanis, and documentary photographer Lewis Bush.

MUSIC FEATURED IN THIS EPISODE

Full Moon Rag by Roy Williams
The Unveiling by Christoffer Moe Ditlevsen
A subtle trace by Martin Landström
Astray by Alec Slayne
Subconscious by Nihoni
Into the Maze by Dream Cave
Ocean Traveler by Calm Shores
Pathfinder by Makeup and Vanity Set
A Neverending Beam of Light by Makeup and Vanity Set
The Man Appears by Makeup and Vanity Set
Reticent (Dimedrol Remix) by Anton Belov
Kern PKL by Limoncello
Dimming Circuit by Limoncello

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View Transcript ▶︎

[SFX: radio tuning SFX; “you’re” ...noise…”listening” …”to twenty”....thousand”...hertz…”]

[SFX: numbers station music & voices montage]

Andrus: Contrary to popular belief that everything is dead outside the internet, there is very vivid and strange, and kind of anthropologically interesting life going on on the shortwave still.

That’s Andrus Aaslaid, a computer engineer from Estonia with a passion for shortwave radio. The weird sounds that you’re hearing right now are recordings from actual shortwave radio stations.

Andrus: You'll be amazed with what you hear from them. And then the music, which is broadcast that is sometimes just literally out of this world.

Andrus grew up in the countryside, on a tiny Estonian island called Muhu.

Andrus: Back then, there wasn't obviously an internet or anything. And in Soviet times, even the TV was showing you broadcasts few hours a day. So you really had to find something to entertain your brain. And my family had several radios.

This was back in the 70s, when Estonia was still part of the Soviet Union. At the time, most radios could tune in to shortwave stations.

Andrus: So I was maybe five, six years old when I enjoyed a lot, just browsing through those bands, because they had all kinds of weird sounds, and then strange voices and strange music and strange broadcasts.

[SFX: numbers station recording montage out]

If you ever listen to music on the radio, then you’re probably tuning into an FM station.

[SFX clip: radio music in

FM signals have pretty decent sound quality, but they don’t travel very far. These signals go straight from the radio transmitter to the receiver, so it’s basically a line of sight situation. That means that if you’re driving in the opposite direction of a radio station, the signal will probably start to break up once you’re about 40 or 50 miles away [sfx: station breaking up]. And if you drive into a deep valley or over a mountain, you’ll lose the signal completely [sfx: radio station sputters out into static].

AM stations are mostly used for talk radio these days. AM doesn’t sound quite as good as FM, but the signal can transmit farther. In the daytime, AM signals can travel about a hundred miles. But at night, these signals reflect off electrically charged atoms in the upper atmosphere, called the ionosphere, and back down to Earth. This allows some of these AM stations to be picked up several hundred miles away.

Shortwave signals do the same thing, but instead of a few hundred miles, these signals can travel thousands of miles, across oceans and entire continents. The audio may sound pretty terrible, but on the plus side, you can basically send a message around the world. That’s why shortwave radio is perfect for vital communication like aviation and maritime traffic control [sfx].

Shortwave is also used by governments, who use it to transmit state-sponsored messages to the people of other countries. For example, here in the United States, there’s a station funded by the US government called Voice of America. They broadcast news into countries without a free press [sfx].

In the United Kingdom, the BBC World Service also goes out on shortwave [sfx].

And some religious groups, like Adventist World Radio, also use it [sfx].

These days, you can buy a basic shortwave radio for about $50. There are also websites that put the entire shortwave spectrum online, for anyone to hear.

Back when Andrus was surfing the shortwave radio bands as a child, he would often hear strange voices repeating a set of numbers.

[music in]

Andrus: The thing that fascinated me most was that there were several stations, which were just reading numbers with a monotonous Russian female voice.

[SFX: Add Russian female numbers station recording]

Andrus: And then did that 24-seven back then, and nobody knew what they were and no adult was able to explain it to me.

What Andrus didn’t know at the time, was that those monotonous voices were likely sending top secret messages to undercover agents.

[SFX: music + numbers station UP, then out]

Olivia: It might seem counterintuitive for intelligence agencies to broadcast top secret messages on the radio. But, that’s exactly what these stations seem to be for.

That’s Twenty Thousand Hertz producer Olivia Rosenman

Olivia: They’re called Numbers Stations, and if you happen to have a shortwave radio, you can tune in to one right now. There’s quite a few of them. And they’re not all reading out numbers in Russian. You can find numbers stations broadcasting in German [sfx], Spanish [sfx], Vietnamese [sfx], Chinese [sfx] and English [sfx].

Olivia: Numbers Stations have been around since the first World War. Back then, these numeric messages were often sent using morse code [sfx]. Later on, voice recordings became more common, but their purpose was the same.

Maris: What they do, they are meant to send a secret message over the radio to the spy or military unit.

That’s Maris Goldmanis, who’s a historian from Latvia. For clarity, we’ve dubbed his voice.

Olivia: Maris studies the history of radio, as well as military and intelligence communications. He runs a website called numbers dash stations dot com, which is an online community of people who research, monitor and record numbers stations.

Maris: It is mainly run from USA. I am one of the main contributors.

Olivia: The thing about numbers stations is they usually just broadcast static. The messages are played at seemingly random times. So if you want to catch one of those messages, you have to spend a lot of time listening. And unless the message is directed at you, you’re not going to understand it.

Maris: You can listen to these stations from your home, but you will just hear numbers. But a person who receives this thing over the radio, he will have to decode this thing, and he will get the message from his decoding work, and he will do what he must do.

[music in]

Olivia: The numbers are read out in groups, four or five at a time. Each number corresponds to a letter, so the voice is actually spelling out words. In order to decode the message, the numbers that are broadcast are combined with another set of randomized numbers. These are written out on a decryption key in the agent’s possession. That key is called a “One-time pad”.

Maris: The one-time pad is a small bit of paper, it contains a code that you need to decipher the number sequence. And afterwards you dispose of this piece of paper.

Olivia: And when Maris says small, he really means it. Visualise a piece of paper so tiny that it can be hidden inside a walnut, or a fake battery, or on the back of a postage stamp. This paper is filled with numbers that convert the broadcast message back to letters. And if you don’t have that piece of paper, there’s simply no way to decrypt the code. That’s why intelligence agencies can broadcast these messages to the entire world with the confidence that only the person with the right one-time pad will be able to understand it.

Maris: The main thing, is that the person who receives this message, is the only person who has access to the decoding information.

Olivia: After the agent has decoded the message, she’ll usually burn the one-time pad.

[music out, sfx: lighter turn on, light burning sound]

Wait a minute, this is starting to sound like something out of Mission Impossible.

Olivia: Totally.

[SFX clip: Mission Impossible clip]

Olivia: That’s because spy movies have taken a lot of inspiration from historical events, especially from World War Two and the Cold War. And that’s when the most numbers stations were on the air.

[music in]

Olivia: Unsurprisingly, no government has ever officially confirmed they use numbers stations. However, there have been a few cases where spies have been caught using them. For instance, in 2001, the US government convicted a group of Cuban spies, who came to be called the “Cuban 5.” The agents had apparently been getting coded instructions [sfx] from a Cuban numbers station on handheld shortwave radios. They decrypted these messages using computer software, which the FBI was eventually able to crack. Meaning they probably should have stuck to the old fashioned paper method.

Olivia: Then, in 2010, the FBI arrested ten alleged Russian spies, who were scattered across the US living under false names. According to the FBI, these deep cover agents were part of a global network of spies run by Russia’s Foreign Intelligence Service. In a Seattle flat where two of these agents lived, the FBI seized a shortwave radio, and a decoding book.

[music out]

Olivia: Cases like these give us a rare glimpse behind the curtain of numbers stations. But most of the time, the exact purpose of any particular station remains a mystery.

Lewis: There's no way definitively to say this is what this is.

Olivia: That’s Lewis Bush.

Lewis: I'm a documentary photographer based in London, United Kingdom.  Olivia: Lewis’ book Shadows of the State explores some of the mysteries of numbers stations.

Lewis: How can I ever prove that this string of numbers is a coded message? With the exception of one or two very rare examples where the codes were broken and then publicized by intelligence agencies, you just can't know.

Lewis: Part of the project is actually about the inherent uncertainty of asking these kinds of questions and actually, for me, that uncertainty is almost the really interesting thing in it.

Olivia: To write his book, Lewis spent three years tracking down some of the physical sites that were broadcasting numbers stations.

[music in]

Lewis: So, the starting point was looking at the efforts that had already been made to locate some of them and slightly to kind of test those theories out a bit, retrace the steps that other people had taken already.

Olivia: For instance, in the late 80s, a retired naval intelligence officer tracked down several numbers stations broadcasting out of Florida. To pinpoint their location, he used an RDF device, which stands for “radio direction finder.” One broadcast was coming from the Palm Beach International airport, while another came from a nearby Air Force base.

Olivia: Today, there are many online communities compiling information about numbers stations—what they say, when they typically broadcast, and their likely country of origin. There are also discord servers, and reddit threads, and freenode channels, and let me tell you, it’s a deep, deep rabbit hole. Lewis used these websites as a starting point for his research.

Lewis: And it ended up being a cross section of using a lot of material from online communities like these shortwave radio monitors.

Olivia: Lewis also used The CIA Reading Room, which is an online database of declassified military and intelligence documents.

Lewis: Which has phenomenal amounts of material, most of it, frankly kind of rubbish but occasionally amongst the rubbish you find a useful piece of information.

Olivia: And finally, there was one other type of website that Lewis used for his research.

Lewis: It sounds kind of bizarre to say this but there are communities of former intelligence agents who basically share stories and anecdotes about their careers on online forums, some of which are not very secure.

Olivia: Not all the information Lewis found there was completely reliable.

Lewis: You encounter a lot of people who, frankly, come across as complete fantasists.

Olivia: When someone claims to be an ex-spy on an online forum, it’s pretty hard to confirm if they’re telling the truth, so you have to take everything they say with a grain of salt.

Lewis: "That’s a really interesting idea, it's a really interesting story, but how believable is it?"

[music out]

Olivia: Using all the information he gathered, Lewis would gradually piece together a general idea of the location of a numbers station.

Lewis: The final step would be to go onto a mapping platform like Google Maps or another satellite imagery provider and spend time basically pouring over the likely area, looking for possible transmitter sites, so something that looked like it could feasibly transmit a shortwave radio broadcast.

Olivia: That meant staring at maps for weeks on end. Because a radio transmitter on a satellite map doesn't look like very much.

Lewis: It's a very tall thin tower. From above, it's almost imperceptible. So the first difficulty is just finding the transmitters and usually all you can see of them actually are their shadows.

Olivia: Sometimes Lewis was trying to find the sites of stations that don’t actually exist anymore, like when he was looking for one run by the East German intelligence agency.

[music in]

Lewis: So like, in one case, with an east German transmitter site south of Berlin and the only clue that it was used as a transmitter site are these strange diamond shaped clearings in a forest and those diamond shapes are the same shape as a particular type of shortwave transmitter.

Lewis: I just felt really strongly this was the right site but I couldn't find anything there that confirmed it until suddenly I saw these clearings and thought, "Hang on, that's weird. Clearings are not normally diamond shaped."

Olivia: In total, Lewis tracked down 30 numbers stations. He published a book that laid out detailed satellite imagery of where they were broadcast from, photographic representations of their frequency spectrums, and transcriptions of their messages.

Lewis: Without saying too much about it, it's been interesting to monitor who's been buying the book in the sense that it hasn't just been people interested in photography and shortwave radio. It's been various institutions that have bought the book. Some of them who have had, historically, quite close relationships to British intelligence agencies and that, again, could be completely coincidental but it's kind of intriguing when something like that happens.

[music out]

Olivia: Today, there are at least 20 or 30 numbers stations still broadcasting. But it seems they’re becoming less common.

Lewis: They're very definitely something that is going out of style and even as I was working on the project, some of the ones that had been live would disappear off the air.

Maris: And now for the most part, it's used by Russia very, very much.

[music in]

Speaking of Russia, there’s one particular numbers station that’s gotten a lot of attention in the last decade or so. It’s called The Buzzer, and some people think it has a more sinister purpose than communicating with Russian spies. That’s coming up, after the break.

[music out]

MIDROLL

[music in]

Numbers stations are mysterious shortwave radio stations that are believed to be sending coded messages to international spies. Over the years, these stations have been used by lots of different countries.

Maris: There was USA, CIA, Cuba, France, Great Britain, Germany, and of course the Eastern Bloc, the Soviet Union, Poland, Romania, and so on. And there also is China, Taiwan, North Korea, South Korea, and Egypt.

Even though numbers stations are a tool of a pre-internet age, it’s the internet that’s allowed people to work together and learn a lot more about them. But even with entire online communities devoted to them, there’s still a lot that we just don’t know.

[music out]

[SFX: Buzzer buzz start]

Olivia: This is a recording of a shortwave radio station that’s commonly known as The Buzzer. It’s broadcast at 4625 kilohertz, and for the most part, it plays this buzzing sound continuously [sfx: continue buzz]. Every now and then, the buzz is interrupted by a voice message.

Olivia: It's usually a mix of numbers and letters, which are spelled out using the Russian phonetic alphabet. For example, where the NATO system would spell out NZTI using “November,” “Zulu” “Tango”, “India”, in the Russian version it’s Nicholai, Zhenya, Tatiana, Ivan.

SFX Clip: Buzzer letter message clip “Nicholai, Zhenya, Tatiana, Ivan”]

Olivia: But every now and again, weird things happen. The Buzzer has played fragments of Tchaikovsky’s “Swan Lake,” a ballet that was often broadcast by state TV following the deaths of Soviet leaders [sfx].

Olivia: Once, it seemed like someone accidentally left the microphone on while they were having a technical issue.

[SFX Clip: phonecall recording]

From what we can understand, this seems to be a phone conversation where the caller is telling an officer from another unit that the signal has gone offline. The officer tells him that he’ll need to talk to the mechanic to figure out the problem.

[SFX clip: phonecall recording out]

Olivia: The Buzzer started broadcasting some time in the 70s. We know it’s from Russia because shortwave radio enthusiasts have pinpointed the transmitter's precise location. Until 2010, it was coming from a military base around 30 kilometres northwest of Moscow. Then, it was moved to a site about 50 kilometres north of St. Petersburg. There’s also a secondary transmission site about 80 kilometres southwest of Moscow.

Olivia: Today, The Buzzer has a bigger online following than almost any other numbers station, with heaps of people tracking every message and variation in the broadcast. And that’s largely thanks to Andrus Aaslaid.

[music in]

Olivia: Andrus first heard about The Buzzer in the early 2000s, back when the internet was mostly filled with weird and random stuff.

Andrus: Mostly you were crawling, starting from one page and then looking at the links and then going slowly to the next one. And you've spent sometimes like half a day, just randomly browsing at your by today's standards, awfully slow internet connection going from place to place and discovering things.

Olivia: But then search engines started to index the internet, making it a bit more orderly and, according to Andrus, a lot less fun.

Andrus: Then when Google and Alta Vista and everything else finally got it under control, it was becoming more like a library rather than just randomly hopping around. Then I think the mysticism came back to the shortwave radio.

Olivia: Andrus bought himself a big, old, shortwave radio

Andrus: A huge Russian one, full tube, made in '52.

Olivia: And reignited his old romance with surfing the shortwave bands. And then one day, shortwave radio popped up in his everyday life.

[SFX: Gradually transform music into: The Man Appears]

Andrus: I had this news ticker always crawling under my main working screen on the computer and all kind of random news was passing by there. And all of the sudden I saw this thing flying around on my screen that the famous radio station UVB-76 has stopped broadcasting.

Olivia: All radio stations have callsigns, which are alphanumeric codes that identify the station. UVB-76 is one of The Buzzer’s callsigns.

Andrus: And I didn’t know what to think about it, but I was a little bit annoyed from the fact that I don't know what the famous radio station UVB-76 is. So I clicked on the news.

Olivia: According to the article, the fact that The Buzzer had stopped broadcasting was important because it meant...

Andrus: That there will be a nuclear war because the Russian dead hand system has now been silent then probably the computers will find soon that Russia doesn't exist anymore and then launch all the nuclear weapons they have towards whatever they think they have to fly to.

[music out, sfx: bomb and debris, then slowdown morph]

Wait! What?!

Olivia: One of the theories about The Buzzer is that the station is a dead hand indicator.

So, what exactly is that? Because it sounds terrible.

Olivia: It’s very very bad. The dead hand is an automatic nuclear weapons control system from the Cold War Era. It’s activated when it detects that Russia is under a nuclear attack.

Which is terrifying. And it sounds like it would just launch nuclear weapons….willy nilly all over the place.

Olivia: Yeah, ultimately it’s a doomsday machine [sfx: doomsday machine start up]. The Russians never confirmed its existence, but there are some people who say it’s still operational today.

Olivia: So the idea is that the continuous buzzing of UVB-76 indicates that all is well, and Russia has not been wiped out. And if it ever stops broadcasting, [sfx: radio silence, computer missile launch sequence] that means it’s time to fire the nukes.

[SFX: Nukes taking off]

Yeah, so that’s supper terrifying. So that means if the buzzer ever went offline, everything is terrible. Probably. And it seems like that’s something that really needs an upgrade.

Buuuut Luckily we’re still here, so...

Olivia: Exactly. It’s actually stopped broadcasting the buzz a couple of times, but it’s always come back online. So I think it’s fair to say that the Dead Hand theory does not explain the Buzzer. But this little incident was enough to arouse Andrus’ interest. And that’s when he decided to put the Buzzer online.

[music in: Kern PKL]

Andrus: I realized that, Maybe I can put that in the internet. And just for the fun, have people listening to that. And then put this scanner at my working computer at home online.

[FROM INTERVIEW TAPE]

Olivia: So wait, I'm not sure I understand. Is it that you had a shortwave radio with an antenna that was somehow feeding audio into your computer, that was then streaming?

Andrus: Yeah, exactly.

Olivia: It took a bit for me to get my head around the idea of a big old Russian radio plugged into a computer and streaming online.

Olivia: So what is it, just like an auxiliary out from the radio and then aux into your-

Andrus: Yeah.

Andrus: Just a very, very simple audio setup, nothing fancy.

Olivia: After Andrus got it set up, people started becoming obsessed with it.

Andrus: I tipped off a couple of tinfoil hat-ish forums that listen to this real time. It's still there, enjoy. And it somehow started to live its strange own life from that moment on.

Olivia: Tens of thousands of people started tuning in.

Andrus: 42,000 people per day has been the biggest number I've seen.

Olivia: People were accessing the site from all around the world. Andrus could tell from their IP addresses.

Andrus: There was a couple of Russian addresses, which were active 24/7.

Olivia: Andrus started to suspect this might be the actual operators of the station.

Andrus: Who are monitoring their feed from my website because those two addresses were consistently on. So they were obviously recording because nobody would listen that much.

[music out]

Olivia: Andrus watched as communities started to form. One group broke off to start their own website called Priyom.org

Andrus: And those guys were fanatics. They gathered information from every source they could.

Olivia: They’ve documented all of The Buzzer’s voice messages since 2010. The date, the exact time of day, the message.

Andrus: Looking at how precise and how elaborate their scheduling system is. I think they might have also gotten some tipping off from people saying when the schedules are.

Olivia: Both this website, Priyom.org, and Maris’ site, numbers dash stations dot com, have VAST amounts of information about intelligence and government communications on shortwave radio. Part of their goal is to fight misinformation that’s mostly come from popular media.

Maris: This subject has been made popular by video games, like for instance Call of Duty.

Olivia: If you’ve ever played Call of Duty: Black Ops Cold War, you might have collected a piece of evidence called a Numbers Station Broadcast, and used it to help you decipher a coded message.

Maris: Also there was a movie called The Numbers Station.

Olivia: The movie came out in 2012, and stars John Cusack and Malin Åkerman.

[SFX: Clip: The Numbers Station Trailer]

Maris: All these popular media references are mainly incorrect, and we wanted to make a site with correct information for people who want to understand the truth about them because last year, for instance, my country opened the KGB documents, and we have found very good proof that these stations were actually used by intelligence agencies and we want to show them as they are.

[music in]

Olivia: By now, you might be wondering why people devote so much time to numbers stations.

Lewis: For me, numbers stations are interesting because they're an opportunity to talk about this world of intelligence gathering and surveillance and really to talk about what, to me, is a total weird contradiction which is this idea that in order to defend democracy, we need to do things that are very undemocratic. In order to protect our way of life, we need to basically license people to go and do things that run completely contrary to this thing that we treasure and value.

Olivia: Numbers stations are supposedly run by intelligence agencies. And intelligence agencies have been known to do pretty shady things in the name of freedom and national security.

Lewis: To me, the problem is if you pursue peace by preparing for war, you actually change the nature of the thing you're pursuing. It's kind of a question of ends don't just justify means, means actually have a very direct effect on the ends that they're pursuing.

Olivia: Even if numbers stations seem a little out of place in the 21st century, the fact is, there are still dozens of them broadcasting today.

Lewis: They are very much a piece of living history. They're something that really is a piece of Cold War espionage, which, for weird reasons, still persists into the present.

Olivia: And both Maris and Andrus think they’re not going anywhere.

Andrus: It's quite likely one of the most foolproof methods of communication with your operatives because as long as the code book is not compromised, it's impenetrable, it's very difficult to track where it's received from.

Maris: While these stations may seem very archaic. They are of course still really valuable, because you can hack everything these days.

Andrus: This is why it has, I think, survived so long and then why it's keeping surviving, because we are getting better and better of monitoring communication between people in the internet domain. So, today the more low-tech you can go to, the harder you are to follow, really.

Olivia: This low-tech approach is famously popular with The Kremlin, and specifically, with Vladimir Putin.

Maris: Vladimir Putin has said, it's best to use typewriter, better than the internet.

[music transition to “Dimming Circuit”]

Olivia: Andrus is also still a big fan of low tech. Even though he now has a world of entertainment at his fingertips, every now and then he still finds himself picking up his 1950s Russian made shortwave radio. And he thinks you should too.

[SFX: numbers stations up]

Andrus: I would encourage people to get themselves an old shortwave radio and just take a drink if that feels good and appropriate, then in the late night, just go to the bands and then listen what's there.

[SFX: numbers station recording montage out]

[music in: Reticent]

Twenty Thousand Hertz is hosted by me, Dallas Taylor, and produced out of the studios of Defacto Sound, a sound design team dedicated to making television, film, and games sound incredible. Find out more at Defacto Sound dot com.

This episode was written and produced by Olivia Rosenman, and Casey Emmerling, with help from Sam Rinebold. It was sound edited by Soren Begin. It was sound designed and mixed by Nick Spradlin.

Thanks to our guests, Andrus Aaslaid, Maris Goldmanis and Lewis Bush. You can find links to the numbers station websites we discussed in the show description. Also, to learn more, check out Lewis’ book, Shadows of the State.

And special thanks to Aigul and Dan Delgado, for translating that snippet of audio from the Buzzer for us.

Finally, if there’s another sonic mystery out there that we should cover, you can tell us on Facebook, Twitter, on our subreddit, or by writing hi@20k.org.

Thanks for listening.

[music out]