In US, you could register your phone in Do Not call list from Federal Trade Commission - https://www.consumer.ftc.gov/articles/0133-cell-phones-and-d...
Relevant quote from FCC Chairman Pai: “Which is the ultimate solution, I think, to this problem, which is to find a call authentication standard.”
And there’s no timeline when that’ll happen. So buckle in, we’ll be here a while.
Each one requires a detailed form to fill out on the FCC site which I send off into the oblivion only to have the call volume go unchanged (or increase). Sorry, tragedy of the commons and all, but it's just not worth it to me to take the time to do this.