...NUMBERS STATIONS...
...A TAD OUT OF THE NORM...
This video is a little trying at times but the information in it might be interesting for some. Numbers stations for those who are unaware, are strictly one-way morse code traffic and they've been around since WW1.
The big deal is that tracking down where the broadcasting station may be is straightforward enough but where the person who receives the message is located is just about impossible to find. Strings of numbers and or letters are broadcast at particular times and mostly start with a few bars of music. The numbers are read out in monotone and the agents whoever and wherever they may be, sit back and take down their part of the message in morse code of course. The listening posts around the world would no doubt record them and if possible, they would decrypt them, however, if a one-time pad was being used there's not much chance of that being a successful effort.
So a fairly secure method of communication. What has this to do with the Somerton Man case? Well, who knows, it could be that they will play a part in resolving the current investigation perhaps...