The contact will immediately be restored to normal communication. Many Samsung phones (especially carrier models) come pre-installed with a smart call manager like Hiya, or you may have installed a blocker yourself. If the above methods don’t show the number, you likely blocked it inside that app.
Open the Phone app (the green handset icon).
Select Settings from the dropdown.
For Samsung Galaxy phones running One UI 5.1 and above (including Galaxy S23, S24, Z Fold, Z Flip series). Steps may vary slightly on older models or carrier-customized versions.