What is a dynamic number that has expired?

The dynamic number has expired means that after a period of use, the mobile phone number can no longer be used. Usually, these dynamic numbers are temporarily used numbers, such as virtual numbers, temporary numbers, etc., and are mainly used for some short-term communication needs, such as account registration, SMS verification, etc. Because the use time of these numbers is limited, after a certain period of time, these numbers will become invalid and can no longer be used.