My Xiaomi three-in-one version can receive short messages but can't send them out. The signal is full, and the number of the SMS center is correct. What's going on here?

If your mobile phone can't send short messages, you can try to restart or change your mobile phone for testing to see if the following conditions exist:

1. 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. SMS inbox and outbox are full.

7. If you want to check whether the SMS function is turned on, you can contact the local manual customer service for processing.

Despite the above reasons, it still cannot be solved. I suggest you contact the local manual customer service or go to the business hall to confirm whether the SMS function is enabled and ask the staff to help you with it.