How to resume the use of Unicom's empty number

If it has become an empty number, you can't get it back, but you can go to the local Unicom's own business hall and ask if this number is on sale now. If no one has bought it yet, you can buy it directly and re-enter the network. I really don't know. You can call the customer service phone number where the number belongs 100 10 for advice on how to buy this number again!