If you have unblocked a number on your phone but they still cannot get through, the block may be occurring at the "Carrier" level (your service provider like T-Mobile, Verizon, or AT&T).
Accidentally blocked a friend, or ready to give a telemarketer a second chance? Unblocking a number is usually quick and easy. The exact steps depend on your device, but the logic is the same: you need to find your and remove the contact. how to unblock phone number