The problem with blocking is that the more hi-tech scammers are making robocalls, and they are programmed to keep changing the number. So you're blocking a number that will probably never be used again.
About the grandson, when that poor kid isn't in an automobile accident, he's locked up in some foreign jail, and needs your money instantly to pay his way out of it. But he doesn't want his parents to know. Amazing that anyone could fall for this.