What is the purpose of number stations on short wave radio?

Question

What is the purpose of number stations on short wave radio?

Answer 1

There are two types of number stations on the air

There are the beacons that send out the same letter or group of letters used for propagation study and for aeronautics

But what most people refer to numbers stations are believed to be stations set up to transmit information to spys and operatives in foreign locals and with those people listening to a normal shortwave radio, it doesn't bring out suspicions in many countries and being able to be tracked like the internet

http://en.wikipedia.org/wiki/Number_stat...

Answer 2

Many believe that number stations may be transmitting spy codes for clandestine operations.  They were used during the Cold War by the Chinese, Soviets, Cubans, and Americans especially.

Answer 3

The numbers are the call sign assigned to that particular transmitter  by the Federal Communications Commission. They are periodically required by FCC regulations to broadcast their call sign. If I'm not mistaken they have to do this at least once every hour. Even Television stations have call signs. That's what the series of four letters is in the television ads when they advertise the news. Here are some links describing the call sign system.

http://en.wikipedia.org/wiki/North_Ameri...

http://en.wikipedia.org/wiki/Radio_call_...

http://en.wikipedia.org/wiki/Television_...