Open the Phone app
Tap Recents
Find the blocked number
Tap the info icon next to the number
Scroll down
Tap Unblock this Caller
Open Settings
Tap Phone
Tap Blocked Contacts
Swipe left on the number
Tap Unblock
Open Settings
Tap Messages
Tap Blocked Contacts
Swipe left on the number
Tap Unblock
Open Settings
Tap FaceTime
Tap Blocked Contacts
Swipe left on the number
Tap Unblock
Open Settings
Tap Contacts
Tap Blocked Contacts
Swipe left on the number
Tap Unblock