Phone cards can't send text messages

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. The 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. We suggest you try again later or avoid the 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. If you want to check whether the SMS function is turned on, you can contact Unicom's manual customer service. Excluding the above reasons can't solve it. I suggest you contact Unicom's manual customer service or mobile phone terminal related technicians.