What do you mean the number has expired?

This number has been cancelled, and there is no such number. When the mobile phone is in arrears for more than a certain period of time, the number will be invalid and can no longer be used. When the user dials the number again, the operator will blacklist the arrears users. Only by paying the arrears can we avoid being blacklisted, so the number has expired. It means that the number has been cancelled, and there is no such number.