If you have an iPhone, there are a variety of methods you can use to screen phone calls. Some will simply save you the ...

From Settings on your iPhone: Tap Apps > Phone > Silence Unknown Callers. Toggle on Silence Unknown Callers.

Once you're on a call with someone, tap the symbol in the left corner of your screen that looks like a sound bar and the recording button. After tapping that button, you and the person on the ...