6. Number Stations Wikipedia
Number Stations (shortwave radio stations of unknown origin) have been reported since World War I and continue to this day. No one knows what their reason is though many people suspect they are coded messages used for espionage (though no country has admitted this). The broadcasts are usually a female voice (though male voices have been heard) and they generally broadcast streams of numbers, words, or letters. They are sometimes apparently random, and other times organised. In the 90s, amateur radio enthusiasts tracked the source of one number station to a US military base. The FCC refused to comment.
Hmmmmm....
