Number Stations: Mystery Over The Airwaves

In the shadowy corners of the shortwave radio spectrum, you can often find mysterious mechanical voices counting off endless strings of numbers — in English, Czech, Russian and German … even Morse code. But who's listening?

The voices are coming from what are known as "numbers stations," and they've long been thought to be part of international espionage operations. In fact, the Russian spies recently captured here in the U.S. may have been getting orders from Moscow via a shortwave numbers station

Additional story at: NPR with on-demand audio
http://www.npr.org/templates/story/story.php?storyId=128586766&sc=emaf
(William Hassig)

The shortwave number stations continue to fascinate

"The very qualities that made the short wave bands attractive to propaganda stations – the ability to blanket vast areas of the planet with relatively low power signals and the fact that they could be picked-up using ordinary radios – made them even more enticing to intelligence agencies. Tune in to the right frequency at the right time, then and now, and you will hear (though not for your listening pleasure) the strangest radio broadcasts you are ever likely to encounter: tinny strains of repetitive folk tunes followed by monotone voices, often synthesized, reading out five-digit strings of seemingly random numbers. These are the numbers stations." Jason Walsh,(Forth link: http://forth.ie/index.php/content/weekend_article/sierra_papa_india_echo_sierra/20100320/ (Kim Elliott)