Don't block them. Either answer them and waste as much of their time as possible or just let it ring until they give up. This takes at least a few extra seconds of the time they could be using to scam someone else.
It's like a broken robocall said Free Security Alarm system, Oh yeah until, someone gets fooled by this insane but ridiculous SCAM, Sorry but this telemarketing nonsense makes you crazy, Ignore it is the best weapon against these evil fraudsters.