Samsung phones

Samsung's website has this article: How do I block unknown or hidden numbers from calling me?

Here's how you enable this feature:

1. Open your phone app.


2. Tap the three dots icon, or the "more" icon.


3. Tap "Settings"


4. Tap "Call rejection" or "call blocking" (you can skip this step on some phones)


5. Tap "Block numbers" or "Auto reject list" or "Block list"


6. Enable "Block unknown callers" or "Block anonymous calls" or "Unknown"

I'm not sure what exactly happens when someone who is blocked calls you. Does their call still show up in the call log? Can they tell that they have been blocked, or does it look like I just didn't pick up? I'll edit this answer once I've tested it out.