Unicom can receive short messages but can't send them. What happened?

Unicom can receive short messages but can't send them. You can restart the phone or change the phone for testing to check whether the following conditions exist:

1. SMS center number is set incorrectly;

2. No signal or low battery;

3. The system is busy during the peak period of holiday SMS sending, please try again later or avoid the peak period of sending;

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.

10. To check whether the SMS function is enabled, you can contact the local manual customer service. If the above reasons cannot be solved, you can contact the local manual customer service or go to the business hall to confirm whether the SMS function is enabled.