The problem is i dont have one of them over priced boxes mine is just a cheap pay as you go phones with my sims card in it and i think it is a android not sure all i wanted was a way to make and receive calls but this does more when my brain works and i remember how to work it. and it has served me well for the most part for the last 10 yrs did have the change the battery out once.There is a way to fix that.
Go to settings, on Iphone,
scroll down to Phone and select.
Scroll down to Silence Unknown Callers.
Select ON.
From now on after completing that, all calls not in your contact list will be routed to voicemail. You will get a notification, but not a call.
Here is an issue with that. I have a call in to a fishing guide that is not in my contact list. I want to answer his call so it's turned off for now, but after talking to him, it will be turned back on.