It's common to discover IMSI-catchers in national capitals around the world. There are many interesting targets.
Washington, D.C. mobile traffic is probably the most spied in the world. Especially now when it's run by technological cavemen and overly confident techbros. Israeli, Russians, Chinese, French and everyone.
Back in the mid-80s, it was an open secret that some AMPS transmissions could be received on ordinary TV tuners which were capable up to Channel 83 or so.
My father being a DXer and installer of a home-built Yagi and rotator system, I discovered this fairly easily. All he told me was to just guard the privacy of these people I was snooping on, because they were supposed to be private conversations after all. I never heard anything of substance anyway. It was one of the more boring surveillance activities of my misspent youth.
The Soviet/Russian station in San Francisco was heavily involved in SIGINT back in the days of microwave radio trunks and analog mobile phones, and I would imagine the Chinese have taken the throne from them today.
Washington, D.C. mobile traffic is probably the most spied in the world. Especially now when it's run by technological cavemen and overly confident techbros. Israeli, Russians, Chinese, French and everyone.