“The phenomenon of so-called “number stations,” mysterious shortwave radio broadcasts that seem to exist only to transmit spoken-word numbers, snippets of weird songs and enigmatic codes, is a genuine mystery.
“Exactly who is broadcasting these transmissions and why is unknown. One theory holds that the transmissions are part of espionage efforts by the intelligence agencies of different countries, another, that they are the work of organized drug smugglers, while still another claims that they are actually communications between extraterrestrial space aliens! (One commentator on an Internet message board even referred to them as “the aural equivalent of crop circles”). The espionage theory seems to be the most plausible. Akin Fernandez, creator of The Conet Project CD, states that, “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.”
“While shortwave radio buffs have been aware of them for years, the number station phenomenon remains largely unheard of by the general public. Below are a series of video clips with examples of these strange broadcasts…” Labyrinth 13
“Generally, numbers stations follow a basic format, although there are many differences in details between stations. Transmissions usually begin on the hour or half-hour. The prelude or introduction of a transmission (from which stations’ informal nicknames are often derived) includes some kind of identifier, either for the station itself and/or for the intended recipient…
“This can take the form of numeric or radio-alphabet “code names” (e.g. “Charlie India Oscar”, “250 250 250”), characteristic phrases (e.g. “¡Atención!”, “1234567890”), and sometimes musical or electronic sounds (e.g. “The Lincolnshire Poacher”, “Magnetic Fields”). Sometimes, as in the case of the Israeli radio-alphabet stations, the prelude can also signify the nature or priority of the message to follow (e.g.(hypothetically) “Charlie India Oscar-2”, indicating that no message follows).
“Often the prelude repeats for a period before the body of the message begins. There is usually an announcement of the number of number-groups in the message, then the groups are recited. Groups are usually either four or five digits or radio-alphabet letters. The groups are typically repeated, either by reading each group twice, or by repeating the entire message as a whole. Some stations send more than one message during a transmission. In this case, some or all of the above process is repeated, with different contents.
“Finally, after all the messages have been sent, the station will sign off in some characteristic fashion. Usually it will simply be some form of the word “end” in whatever language the station uses (e.g. “end of message, end of transmission”; “Ende”; “fini”; “final”; “konets”). Some stations, especially those thought to originate from the former Soviet Union, end with a series of zeros, e.g. “000 000″; others end with music or other sundry sounds. Due to the secretive nature of the messages, the cryptographic function employed by particular stations is not publicly known, except in one or possibly two cases. It is assumed that most stations use a one-time pad that would make the contents of these number groups indistinguishable from randomly generated numbers or digits. In the one definitely known case, the former state of West Germany did use a one-time pad for numbers transmissions…” Wikipedia
A 4 CDset of number station recordings, The Conet Project, can be downloaded here…