Unicom's mobile phone number SMS said that the mobile phone number entered the validity period from the recharge period. What does that mean?

When the account balance of prepaid mobile phone users is not enough to deduct the monthly fee of the package, the account will enter a 90-day recharge period from 0: 00 the next day; During the recharge period, you can re-enter the validity period by recharging. If after you recharge, the recharge amount is still not enough to deduct all expenses, then your account is still in the recharge period and needs to be recharged until the account balance is greater than zero. You can check your account balance in the following ways: 1. Log in to the online business hall /sAAGm and enjoy a 20% discount!