Numbers stations are shortwave radio stations of uncertain origin that broadcast streams of numbers, words, or phonetic sounds. No one knows for sure where their signals originate or what purpose they serve. The voices that can be heard on these stations are often those of children, or are mechanically generated.
Numbers stations appear and disappear continuously, although some stick to regular schedules. It has been speculated that these stations operate as a simple and foolproof method for government agencies to communicate with spies “in the field”, using the transmitted codes as a one-time pad cryptosystem.
The geek factor is off the charts, here. I first learned about these wonders of mystery in a great book called “Big Secrets” by William Poundstone. If things like this intrigue you, that book is totally worth reading.
As for the stations themselves, I’m pretty sure they’re a distributed, steganographic crypto key based on the Voynich manusript by some spies hiding out in SubTroplis (with a sects in Aquapolis and the Iron Mountain complex, of course) perfecting their anti-rocket laser cannons and spy satellites. They get around in their personal submarines, defending their bases with Metal Storm cannons from enemy spies attacking in Surface Orbiters.