How can I Block Spam Calls from +234 County?

Unfortunately you cannot block an entire area code or country code. The best you can do is individually block each number as it comes in. Sadly, that is time consuming and not always effective since spammers have access to many, many different numbers.

From what I understand, you can add the area code as a contact and it is supposed to work (+1 (###)). It doesn't seem to be for me though.