This article explains how to unblock a contact on an iPhone or iPad. The exact menu names may vary slightly for different OS versions, but the basic steps still apply.
How to Unblock a Contact/Phone Number on iPhone
If you've previously blocked a number on your iPhone or iPad, here's how to unblock it so the contact can call, text, email, and FaceTime you again:
Open the Settings app.
Tap Blocked Contacts.
