Cuba’s Mysterious ‘Numbers Station’ Is Still on the Air 5

Illustration: Shaye Anderson

Illustration: Shaye Anderson

by Joshua Kopstein, Motherboard

On August 18 at 22:00 UTC, I heard a government intelligence agency transferring encrypted messages to spies over the radio.

Or at least, that’s the most common explanation for what I heard.

I dialed to the correct frequency—17480 kHz—using an internet-connected radio tuner maintained by a university in the Netherlands. Suddenly, over waves of static, an eerily-robotic woman’s voice began speaking a series of five-digit number sequences in Spanish.

About three minutes later, the numbers repeated in the same order, but this time each sequence was followed by a digital bell-like tone and a harsh blast of noise, like a 56K modem trying to connect to AOL in the 90s. This continued for about 20 minutes, each sequence punctuated by the bizarre noise blasts.

Then, static.

This is HM01, sometimes called “Voce De La Chica,” a shortwave numbers station believed to be operated by the Cuban intelligence directorate, Dirección de Inteligencia (DI).

To the casual listener, numbers stations are mysterious broadcasts of voices speaking streams of numbers which, in at least some cases, are encrypted messages being sent to government spies.

They have long seemed like Cold War relics, born in a time when spying meant boots-on-the-ground and internet surveillance was impractical or irrelevant. And yet, HM01 continues to operate in what the NSA has called a “golden age” of internet-enabled signals intelligence, and despite historic progress in US-Cuba relations earlier this summer.

While evidence suggests HM01 is operated by the Cuban government, it’s virtually impossible to tell who it’s sending to, which is one of the main tactical advantages of numbers stations: You can easily see the intended recipient of an email, but you can’t prove someone listened to a radio broadcast unless you catch them in the act.

Shortwave radio listeners (or SWLs, as they are known) have followed stations like HM01 for decades. According to members of, an online community of radio enthusiasts that monitors numbers stations, HM01 is a close relative of “Atención,” a government station that has operated for decades and whose transmissions wereused as key evidence in a case that convicted five Cuban spies in the late 90s.

Article continues here: HM01






Reception of Cuban Spy Numbers Station HM01 on Tuesday, August 4th 2

By Bulgarian DX blog

CUBA   Reception of Cuban Spy Numbers station HM01 on Tue, August 4

from 0630 on 11462 secret / hidden tx ?Bejucal? Spanish Tue/Thu/Sat

from 0745 on 13435 secret / hidden tx ?Bejucal? Spanish Tue/Thu/Sat

from 0815 on 11635 secret / hidden tx ?Bejucal? Spanish Tue/Thu/Sat

Editor’s Note:  High Frequency (HF) radio broadcasts — better known as “shortwave” or “ham radio” — have been the workhorse of Cuban Intelligence communications for decades. That said, Havana’s use of HF radio for espionage continues to decline, most likely as its spies transition to internet-based means.

As Normalization Effort Continues, Cuban Spy Broadcasts Continue…… 3

numbers stationsAs expelled spy-diplomats Josefina Vidal and Gustavo Machin push for greater US concessions, their spy colleagues continue to go “old school” in targeting the US…..

Recent Cuban “Numbers Stations” broadcasts from Havana to the regime’s spies abroad:

February 9th

February 8th

February 6th

January 20th

January 16th


Numbers Stations: A Bad Day to be a Cuban Spy 1











By Thomas, The SWLing Post

While band scanning last Sunday (September 8, 2014) I stumbled upon the Cuban numbers station HM01 on 11,530 kHz at 17:30 UTC.

It’s always intriguing to hear shortwave numbers stations, but I prefer those that stick to pure vocal number strings; HM01 has numbers with digital bursts between number sets, which is a more fatiguing listening experience.  Nonetheless, I kept it playing in the background as I tooled around the radio room Sunday afternoon, putting away supplies from my recent three week road trip.

Several times during the HM01 broadcast, I heard the audio (not the AM carrier) drop in the middle of numbers sets and digital bursts. This isn’t the first time I’ve heard hiccups on HM01 (see this post from last year, for example), so I wasn’t terribly surprised. Then, close to the top of the hour, HM01 audio dropped for a minute or so, then switched back to five-number sets with no digital bursts between; though I wasn’t copying the message, I suspected that someone in the studio intentionally, perhaps in frustration–or else accidentally–started the broadcast from the beginning again.

At this point, I started recording. The five-number sets continue for about a minute, then the carrier unexpectedly drops:

Feature continues here with audio: Cuban Numbers Station


Espías cubanos todavía dependen de tecnología anticuada como la onda corta y clave Morse 3

Juan O. Tamayo,

No importa si usted no es un espía cubano. Usted podría recibir mensajes secretos enviados por La Habana a sus agentes en Miami, Washington y otras partes del mundo.

Cada semana, una estación de onda corta en Cuba transmite 97 mensajes codificados en tonos que parecen de fax. Un programa de computadora fácilmente disponible al público cambia los tonos en números, y entonces los espías cubanos decodifican los números en palabras.

Una segunda estación espía transmite 16 mensajes por semana en los puntos y rayas del código Morse, de 175 años de antigüedad, mensajes secretos para aquellos espías de La Habana de más edad o menos conocimientos tecnológicos.

Dieciséis años después de los arrestos en Miami de cinco espías cubanos que recibían sus órdenes secretas por transmisiones de onda corta, La Habana continúa usando un sistema que ha caído en desuso en el mundo del espionaje desde el fin de la Guerra Fría.

Hay muchas maneras más modernas y eficientes de comunicar secretos usando satélites, transmisiones por ráfagas, correos electrónicos únicos, etc., dijo Chris Simmons, oficial retirado de inteligencia del Pentágono especializado en asuntos cubanos.

“Pero estas transmisiones cubanas podrían ser para viejos espías, dinosaurios que llevan mucho tiempo escuchando (onda corta), agentes a largo plazo, que se sienten cómodos así y no quieren ni necesitan cambios”, añadió Simmons.

La estación cubana más ocupada en estos tiempos, y la única estación espía del mundo entero que usa los tonos de tipo fax, ha sido bautizada como HM01 por radioescuchas aficionados que tienen websites tales como Spooks List, Spynumbers, ShortwaveSchedule y Enigma2000.

La misma transmite de 11 a 14 mensajes por día, un total de 96 por semana, en el mismo horario cada semana pero usando una docena de frecuencias de onda corta, dijo Chris Smolinski, de 41 años, ingeniero informático de Maryland cuyo hobby es vigilar las estaciones espía.

Cada mensaje tiene casi siempre 150 grupos de cinco dígitos, de modo que los radioescuchas no pueden medir la verdadera longitud del texto, y algunas de las transmisiones de 10 minutos son falsas, diseñadas para encubrir el verdadero número de espías que las reciben.

Cualquiera puede conectar un receptor de radio a una computadora, donde el programa DIGTRX —usado por muchos radioaficionados para enviar y recibir textos largos— convierte los tonos en números. Los espías usan entonces programas secretos para convertir los números en texto.

“HM01 es un sistema ideal porque no hay que enseñárselo a nadie. La computadora hace todo el trabajo”, dijo Smolinski.

Lea más aquí: Espías cubanos todavía dependen de tecnología anticuada como la onda corta y clave Morse

Communication Schedule for 23 Current Cuban Spies 1

Schedule and frequencies for Cuban Spy Numbers maintains this listen of reported High-Frequency (HF) radio broadcasts to Cuban agents in the field. Also known as “shortwave” or “ham radio,” HF broadcasts have proven themselves as a highly effective means of communications for decades. While such broadcasts can be intercepted, an abundance of low-cost encryption systems keep the sent message secure. For added security, Havana uses a standardized message format of 150 five-character groups. This technique prevents the listener from gaining insights based on the brevity or length of the broadcast.

Cuban Spy Communications Intercepted Yesterday 3

A shortwave radio (High Frequency) enthusiast recorded this “Numbers Station” broadcast yesterday. Thirty-two seconds into the video, you will hear distinct tones before the automated female voice begins the broadcast.

In the past, a “Numbers Station” broadcast would always consist of 150 five-number groups. Over time, Havana migrated to this hybrid broadcast, consisting of sporadic voice laced together with the digital transmission of compressed data. This evolution both lessens the possibility of errors made by the receiving spy and allows for the transfer of infinitely more information. The Cuban spy will use a cipher program to automatically decrypt and decompress the recorded digital signal.

Other recent intercepts:

October 1, 2013
Cuban Numbers Station HM01 @10715 kHz SW AM
Recorded in Hamina, Finland

September 28, 2013
Overlapping messages from the Cuban Numbers Station
Location unknown

September 26, 2013
Cuban Numbers Station HM01 @10715 kHz SW AM
Recorded in Hamina, Finland

August 31, 2013-10-24
Cuban Numbers Station HM01 @17480 kHz at 2209 UTC
Recorded in Northeast Ohio, USA

Cuban Spy Broadcast Using “Numbers Station” 1

Editor’s Note: Historically, the Cuban Numbers Stations broadcast messages consisting of 150 five-character groups. The uniform appearance of these broadcasts were intended to mitigate efforts by other spy services who sought to gain insights by profiling broadcasts. These newer, hybrid broadcasts merge “old-school” voice with digital transmissions. Also known as “compressed” or “burst” transmissions, the latter allow the shipment of exponentially more information with shorter broadcast times.

Shortwave Radio Broadcast to Deployed Cuban Spy – Recorded Late March 2013 4

HMO1 Cuba Spy Numbers 11635 khz am @0520utc

Nice four minutes of the start of HM01, a Cuban “Spy Numbers” broadcast featuring a traditional female announcer with switch to data using Winradio Excalibur pro and wire antenna. QTH is Tampa Florida and as you can hear, the signal strength is really strong.