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, trash icon, or Unblock next to the number
Confirm if prompted
Open the Contacts app if the number is saved there
Open the contact
Tap the three-dot menu
Tap Unblock contact if available
Open Messages if the number was blocked there
Open the conversation
Tap the three-dot menu
Tap Unblock number if available
Check your phone’s spam or call blocking app if the number is still blocked
Remove the number from any blocked list there