Open the Phone app
Tap Recents
Find the blocked number
Tap the info icon next to the number
Scroll down and 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 Phone
Tap Silence Unknown Callers
Turn it off if needed
Open Settings
Tap Phone
Tap Call Blocking & Identification
Review any call-blocking apps or filters
Remove or adjust the app settings if needed