The numbers they call are not necessarily random. I was torturing one “reduce your credit card fees” guy by giving him 3 wrong credit card numbers in a row. He got mad and started threatening me with terminating all my credit cards - which was hilarious because just the moment before he was asking their numbers. But then to substantiate the threat he disclosed what knows about me. My address, my phone, my car make… the only thing they got wrong was my name - they used my son’s name instead of mine.

And other callers called me my son’s name a couple other times. So there seems to be some database that some of them share.

Phone number often yields address, which often yields street view for the car make. Doesn’t sound like they had thaaaat much.

Well, I have 3 cars, 2 sons and 1 daughter (and me and my wife are still alive too, you know). But robocallers are stuck with the same car and the same person: 1/15 one occurrence, 0.0000013 five occurrences.

I would expect a phone company to throttle multiple failed dial attempts to nonexistent numbers. Otherwise you could DoS the system.

Shoot, in the old analog days, you could literally get the physical tumblers in the telco's switch to stick in an incomplete state and create a party line. DoS'ing the phone from too many wrong numbers is the least of the issues here.

There is definitely more to that - I'm on a pretty common 650 area code, and my spam calls have gone down from 1-2 / day a year ago to less than 1 every couple weeks.