Why is my Unicom mobile phone suddenly unable to send messages? The number of the SMS center is correct. What happened? C, come and answer

If the mobile phone can't send short messages, you can try to restart or change the mobile phone for testing to see if the following conditions exist: 1. The SMS center number is set incorrectly; 2. No signal or low battery; 3. Because the system is busy during the holiday short message sending peak period, it is suggested to 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 sending box are full; 10. Query whether the SMS function is turned on; If the above reasons cannot be solved, you can contact Unicom's manual customer service for processing.