Intro to Numbers Stations

These transmissions which many people find to be a mystery are coded messages that are made from a list of numbers, Morse code, or even polytones. Numbers stations are used to transmit coded messages to spies and is encrypted with a one-time pad. With the use of a one-time pad, there is no way to decode the message that is transmitted.

Only the person who has a copy of the one-time pad would be able to decode the message. This allows for complete anonymity which is why it is used for covert operations. With the message being sent through a SW broadcast the message can be heard from long distances and the identity of the people involved in the operations is kept secret.  The time pad is only used once and destroyed after use to maintain its security.

Crypto Museum OTP
[Example of a genuine one-time pad booklet, picture from the Crypto Museum]

Each station is usually given a name depending on what is included in the broadcast.  For example, G03 is given the name “Gongs or Chimes” since its intro and outro signal includes the sounds of gongs.  Many Morse stations do not have nicknames though since they do not include anything specific that differs them from another.

Almost all number stations include a few common elements which are the ID, group count, and message.  The ID is the group of numbers that indicates who the message is intended for, the group count is how many groups of 4 or 5 digit numbers that are sent in the message, and the message is what the recipient is ultimately going to decode to get his or her orders from.  Every transmission usually has an intro or end phrase, such as “ende” or will just end with numbers (ex. 000 000).

Many number stations are well known because of the music that they play.  This has become less popular with today’s numbers stations, but there are still a few such as E25 or V13 that use them.  There also used to be more stations that read their numbers with a live voice, but now there are no more stations like this.  Voices that are synthesized and created by machines are used instead.

Government agencies are reluctant to admit operating any numbers stations, and so there are almost no confirmations of any government running them other than the Polish Institute of National Remembrance. Although there have been several cases where spies had been arrested such as the Cuban Five who were arrested for spying since they had received and decoded messages from Cuban numbers stations. There has also been the case of a Russian couple who were arrested for decoding Russian polytones from XPA.

Schematics showing modern use of numbers stations by Cuban spies. From Spycraft: The Secret History of the CIA's Spytechs, from Communism to Al-Qaeda.

Schematics showing modern use of numbers stations by Cuban spies. From Spycraft: The Secret History of the CIA’s Spytechs, from Communism to Al-Qaeda.

Naming System

First created by ENIGMA is a system to categorize stations by what language (or mode) they use:
E – English
G – German
S – Slavic
V – Other Languages
M – Morse
X – Noise
XP – Polytones
T – Unknown (Removed)

Other Prefix’s Used

SK – Digital Mode
HM – Hybrid Mode
DP – Digital Pseudo-Polytone


English: E06, E06a, E06b, E07, E07a, E11, E11a, E17z, E25, E25a
German: G06, G06a
S06, S06b, S06c, S06e. S06s, S11a
Other Language: V07, V13, V21, V24, V26, V30
Morse: M01, M01a, M01b, M01c, M03, M08a, M12, M12a, M14,
M14a, M18, M24, M24a, M51, M51a, M97, MX
Polytones: XPA, XPA2, XPB
Other Mode:
HM01, DP01

Total: 44


A Scene from the Soviet movie “TASS is Authorized to Announce..” 1984.  A CIA Agent in Moscow codename Trianon receives numbers stations broadcast