In my case (Android) I'm on every no call list you can be on, and I also only allow calls to come through from contacts.
A few slip through now and again, but the frequency is very low.
Smart thing to do is to never, ever answer. If you answer, they know they caught a potential target. That gets around, so the frequency of calls goes up.
I Never answer unknown numbers
Airplane mode is your fren
In my case (Android) I'm on every no call list you can be on, and I also only allow calls to come through from contacts.
A few slip through now and again, but the frequency is very low.
Smart thing to do is to never, ever answer. If you answer, they know they caught a potential target. That gets around, so the frequency of calls goes up.