There's a radio station in Colorado Springs called KTLF. Every evening from 7P to 5A they play instrumental Christian music with hourly station identification breaks. (You can find it on Tune-In)
When I was working nights that's what I listened to because I didn't have to think to enjoy it.
One night at FedEx I was doing paperwork and had the radio going when the music faded out and I heard a computer voice reading 4 digit sets of numbers.
1234, 2345, 3456, 6789 (that's just an example) then it would fade out and I'd hear nothing for a minute and the music would come back. It did that from about 2A to 4A. Every 20 minutes or so.
That's a really short video I was able to get. That's me sitting at my desk.
It happened two or three times while I was working there and I never figured out what the cause was.
I did some research and found out that there is a thing called a number station but they are usually on shortwave. Most of them are known and you can dial in and listen to them.
It's generally believed that they're radio stations sending coded messages to intelligence agents in foreign countries.
They broadcast from all over the world but no country in the world will admit that they operate number stations.
North Korea broadcasts a numbers station to South Korea but that's the only one in the world known to be on FM.
