If you are fortunate enough to be somewhere that electromagnetic clutter is thin enough to still receive Shortwave radio you will occasionally run across stations just reading off numbers.
I watched a movie, “Numbers Station”, that postulated that the purpose of these stations was to provide a mechanism for covert military or intelligence agencies to get information to their operatives in the field.
In 1960, this would have made sense, but today with modern satellite communications technology and modern encryption technology, it doesn’t.
Why would someone broadcast over such a wide area at such high power that these stations could be heard globally to provide very limited bandwidth for communications that would be so easily jammed when discrete directed satellite communications which is readily encrypted beyond recognition could be used?
None the less, the available evidence seems to support the movies premise. Take a look at the wiki on the subject. The evidence would also seem to support a second premise of the movie, that it’s common for such agencies to eat their own. Maybe there is hope in that.