Unicom's mobile phone can't send short messages, but can only receive them. What is the reason? Thank you, friend.

If you can't send and receive SMS, you can try to restart your mobile phone or change your mobile phone to test whether there are any of the following situations: 1, the number of SMS center is set incorrectly; 2. There is no signal or the battery of the mobile phone is insufficient; 3. The system is busy during the peak period of holiday SMS sending, so it is suggested to 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 mobile phone shields the short message sending function; 6. Blacklisted by SMS; 7. Insufficient quantity balance; 8.SMS inbox and outbox are full. If the above situation has not been solved, it is recommended to contact the local manual customer service for handling.