Open the Phone app
Tap the three-dot menu or More
Tap Settings
Tap Blocked numbers or Block numbers
Find the number you want to unblock
Tap the X, minus icon, or Unblock next to the number
Confirm if prompted
Open the Contacts app if the number is blocked there
Select the contact
Tap More or the three-dot menu
Tap Unblock contact
Open Messages if the number is blocked in texting
Open the conversation
Tap the three-dot menu
Tap Unblock number or Unblock contact