This is a recording that I made with my mobile telephone, (sorry for the inferior quality), of a spy numbers station on shortwave, run by the Russian Intelligence Agency GRU. The station is named E07 by the famous numbers stations monitoring group Enigma. The message, to the spy or agent, is coded and they are probably using so called one-time pads. That is, the key to the codes are only used once and therefore it is not possible to understand the message. OK, but why then are they using plain voice via a shortwave transmitter? After all, this is not the 20th century?
Elementary my dear Watson, It is impossible to trace the recipient this way, contrary to a message sent by regular mail or via the internet! As I have demonstrated by this simple video it is easy to listen to the coded messages even with a small shortwave radio!
For more information regarding this particular spy station: