All thru WW2 messages like that were sent daily via radio to occupied europe. The D Day invasion and its documentation in movies made those specific messages widely known.
This kinda thing has happened since radio became a tool for communication, regardless of the type. The movies just publicized it to the general public.
The whole deal of spying and comms and crypto during the war is fascinating. Starting with the pols almost completely breaking the enigma machine coding before the nazi's invaded. They gave a machine, I'm talking home made rudimentary analog computer.....using that word in the loosest of terms...the size of a small house, to the Brits who along with the allies broke the basic coding methodology. Thru the end of the war and beyond.
This also went on all over the world where ever people were working behind enemy lines.
It goes much deeper than just the messages.