Hi Lisa here, and I'm going to show you how you can block a phone number on your Iphone. So first thing you have to make sure, is that the phone number has to be a contact in your phone. So once you've made that contact, you can decide that you want to block them.
So for me, I'm a little mad at my sister right now, so i'm going to block her. So in your settings you can scroll down to your phone, and scroll down again and you'll see blocked. Tap on that, and you'll see add new, you tap there, and it'll bring up a list of all your contacts, so I'm going to search for her, and once I see her there I can tap on her name, and then she'll be blocked. Now I won't receive any phone calls, text messages, or face-time request from her. So that's how you block a phone number on your iPhone.