This is the most common method as it allows you to see your entire "Blocked Numbers" list in one place. Open the from your home screen.

If the number is auto-blocked as spam:

If the person you want to unblock is already saved in your phone’s address book, you can unblock them directly from their profile. How to Unblock a Number on an Android Phone - Avast

If you are using an older Samsung device (such as a Galaxy S6, S7, or J-series), the pathway is slightly different.

: Tap the green phone icon on your home screen.