Spam phone calls

Are spam phone calls a significant problem throughout the world as much as here in the USA?

Lately, 95% of the spam calls have a fake number that is similar to my own. Is there a way to halt this? Is there any research as to how many of these calls originate in the USA? Phone calls originating outside the USA could be tagged as such even if I happen to use my USA cell phone in Iceland.

Way back when phone calls cost money, junk mail was king. If only 2% of junk mail recipients responded, it was considered a successful mailing. What is considered a good return for spam phone calls? One in ten thousand?

(and this is an IMHO) How about a one cent tax on any phone call in which the recipients hangs up within ten seconds. Sure, it would probably add 10 cents to my phone bill when I dial wrong numbers. OTOH, how do we collect from foreign phone calls?

Cayman Islands here. No problem. In the last three months I have received one vaguely spamish call. One. And that was from the place I last got my oil change calling to say it was time to schedule another oil change. Certainly not a random Rachel-from-Card-Services type of spam call.

Foreign phone calls pay a landing fee. If you wanted to, you could increase the landing fee and offer a rebate.

OTOH, the reason they can do it now is because they’ve negotiated/worked out a way to avoid paying high landing fees. I don’t know how that works, but it probably involves, at least partly, a dedicated channel that is not seen as multiple calls.

(We get spam calls. It does vary: some numbers I’ve answered get a lot more spam calls of some specific type than others do)

With essentially free VOIP services, and totally legal caller ID spoofing, there is no solution except to pay the phone company to only allow Whitelisted calls through.
That has its drawbacks too, but there is no solution.

I get 3 to 7 calls a day, on the cell and home lines. I’ve just turned off the ringer. If someone wants me, they can text, but I’m sure that will be the next bastion of mass spamming.