How do I block unknown callers?

Tap Settings > Blocked numbers and add the number you wish to block.

You can also block unknown numbers from this menu by toggling on Block unknown callers.

The second option is to block calls from your list of recent calls.

Tap Phone > Recents.

How do I block No caller ID on my Android phone?

From the phone app tap More > Call Settings > Call Rejection. Next, tap ‘Auto reject list’ and then toggle the ‘Unknown’ option to the on position and all calls from unknown numbers will be blocked.