My Unicom card can't send short messages, but my mobile card can. They are all on the same mobile phone, and there is no arrears.

According to your situation, there are several reasons why mobile phones can't send text messages:

1. SMS service is not enabled on the mobile phone. You can contact the local manual customer service or activate this function in the local business hall.

2. If the SMS center number is not set or set incorrectly, just reset it;

3, the signal is weak, there is no signal or the battery of the mobile phone is insufficient, resulting in the information not being sent normally;

4. Because the system is busy, especially during the peak period of sending short messages on holidays, it is suggested that you try again later or avoid the peak period of sending short messages;

5. The sending format is incorrect. If you send a short message to PHS users, you need to add the area code before the number;

6. SMS sending and retention is valid for 24 hours;

7. Whether the SMS inbox and sending box are full;

8. It is recommended to restart the machine or change the phone to test it.

You can solve the problem simply. If you still can't send a text message, you can contact the local manual customer service.