Always stick these numbers on your phone & list them as “dont answer” or “scam.” I do this with clients that I’ve been warned against as well.
Har. Up here in Canada, we get tons of calls like that from the US. Either direction, it’s a way for them to stay just outside the respective “Do Not Call” laws since calls from outside the country don’t/can’t fall under the rules.
Neither the FTC in the US or the CRTC in Canada can actually do much about them. Nor can the FTC stop them from calling Canada or vice versa.
They all need to suffer a nasty illness. Maybe something to do with their ears would be poetic.