My experience with scam callers has been that if you pick it up, they will keep calling because they flag your line as live. At one point, back when I'd answer and threaten to report them, it would be at least one call an hour, every single day. Since I stopped picking up, I rarely get calls anymore unless there's a data leak with a company I use. Then I'll see a little ramp up for a month or two before it dies down again.