If they sound old enough that they went to school before the curriculum was entirely about "how men ruined the world for the other 3,748,281 genders, how white people ruined the world for everybody else, and why you should neuter yourself and get a man bun and otherwise do what the authorities tell you to do" I use agent 271828. If they don't hang up immediately I follow up with "Sir, spoofing your caller ID is a Federal crime. Please stay on the line for a few moments while we get your real information and location. Are you calling to report any other crimes you have committed?" .
(Name of town) home for wayward ex military and unwed fathers. Who's your daddy, and we'll see if he's here.
I tried an imaginary number once because I thought they wouldn't recognize it, but nobody would believe I was "agent square root of -1" and when I tried "agent i" they thought I was a Rastafarian and accused me of being one of those white posers that get hair salon dreadlocks.
Get a phone number with an area code from a long distance away from the one you live in. That way if anyone from that area code calls you know it is a scam.
who sits there and listens to obvious BS on the phone? - same same as clicking on spam crap >>>> anything official won't be calling you up - and if by the wildest chance you get a call from something that sounds legit - get full ID of the person and a return phone # >>> call back and verify the info given ... getting catfished by some azzhole is just being gullible & naive and not at all a good prepper trait to have ...