Open the Settings app
Tap Phone
Tap Blocked Contacts
View the list of blocked numbers and contacts
To check blocked FaceTime contacts
Open Settings
Tap FaceTime
Tap Blocked Contacts
To check blocked Messages contacts
Open Settings
Tap Messages
Tap Blocked Contacts
To unblock a number
Tap Edit in the top right
Tap the minus icon next to the contact
Tap Unblock
Tap Done