My experience is the same, 90% of unsolicited calls I get are from the same area code and prefix, only the last 4 digits are new.

I love how it makes it really easy for me to screen the calls however, as no-one I know has the same prefix and there are a couple area codes covering the local calling area.

While that's true, I've never seen a system that will randomize the spoofed number on every call. We regularly see the same number show up on our caller-ID for weeks on end. In fact, in one case the "I'm calling from Windows" people had their caller ID changed to "DO NOT PICK UP" for a few days, I'm guess by a disgruntled employee.

So I think a database would help if it could be updated in near-real time. If 100 people across the country get a call from the same bogus number, it could get added immediately and stop thousands more calls from going out that night, at least.

Having handled a lot of dialer traffic, the less scrupulous will randomize their numbers. My proof of this is that we monitor call statistics, including the ratio of connected calls to attempts, and short calls (under 6 seconds). Carriers often have a strict rule of how much crap traffic they'll take (like no more than 20% can be short calls).

When we implemented caller ID based blocking, our mix of crap traffic stayed the same. Just instead of getting "good" dialer traffic, we'd just get the bad randomizers. This is because the carrier sending the traffic would tune it to make sure they never exceeded the 20% short call limit. Even at the volume we were doing (hundreds of millions of calls a day), there seemed to be a limitless supply of dialer, good and bad.

I've gotten the same robocall for house security systems from totally random area codes every time.

I wonder if services like trello are being used/abused for these. (And is unsolicited robo calls against their TOS?)

I've gotten those before and iirc there's a press # to not call again and it's worked so far. Same with the solar tax credit calls but those came back every few months from a new number until recently.

> trello

You're looking for Twilio.

You are correct.