What is the reason why mobile phones can't send short messages?

Mobile phones can't send short messages. There are the following situations:

1. Whether the SMS center number is set correctly, please enter the correct SMS center number;

Second, there is no signal or the mobile phone battery is insufficient;

3. The system is busy during the peak period of holiday SMS sending, so it is suggested that you try again later or avoid the peak period of sending;

Fourth, the short message sending time exceeds 24 hours;

Fifth, the mobile phone shields the short message sending function;

6. The other party's number is blacklisted;

7. Insufficient quantity balance;

Eight, SMS inbox and outbox are full.