1. The SMS center number is set incorrectly, please re-enter the correct SMS center number;
2. No signal or low battery;
3. Because the system is busy during the holiday short message sending peak period, it is suggested that you try again later or avoid the sending peak period;
4. The sending format is incorrect. If you send a short message to PHS users, you need to add the area code before the number;
5. The short message sending time exceeds 24 hours;
6. The mobile phone shields the short message sending function;
7. Blacklisted by SMS;
8. Insufficient quantity balance;
9. SMS inbox and outbox are full.