Although no law will prevents all scams, some European governments do have much stricter laws on when you can "cold call" period. In Germany, for instance, thanks to legislation passed a decade ago, I believe the customer needs to grant explicit permission in order for a business to be able to cold call, and no telemarketer can impersonate your phone number -- https://www.thelocal.de/20090804/21021.

It would be interesting to see if there is a correlation with these sorts of laws, and the prevalence of phone scams.