Quick, find your old analogue dial up short wave radio stations

[Cactus Annie]

^ When I was 13 my mum bought me a Sony CFS-W308L double deck four band radio on which I used to spend hours recording room noize, putting songs in high speed dubbing and fiddling with the knob on the dial up radio. My curiosity was particularly aroused whenever I heard either morse code beeps, or a man or a woman randomly reading out a series of numbers. There was never any explanation for these 'stations' and when I asked my mum she didn't know what they were either. It wasn't until I was looking through a book by an investigative journalist that I found the answer to these so called number stations. This revelation was very exciting and a little creepy. Number stations are in fact messages given by various national secret services to their representative spies!

http://speechificationaudio.s3.amazonaws.com/BBC_R4_Tracking_the_Lincolnshire_Poacher_24112006.mp3

Numbers station - Wikipedia, the free encyclopedia

I also flicked through Spycatcher by Peter Wright (former MI5 agent) and mentions of countries using short wave radio messages is mentioned numerous times