From within the Settings app, scroll to and tap Apps.
Scroll to and tap Phone.
Scroll to and tap Blocked Contacts.
Tap Add Blocked Contact.
Enter the name of the contact you'd like to block, then select their name from the filtered list.
When a contact is blocked you'll no longer receive phone calls, messages, or FaceTime from them.
Tap Block Contact.
When a contact is blocked you'll no longer receive phone calls, messages, or FaceTime from them.
To unblock a contact, swipe left on their name.
Tap Unblock.
You've completed the steps!
