The mail system service has not been restored.

2. It is possible that the signal is unstable, try to change a position.

3. Can I send messages when trying to replace other SIM cards?

4. Determine the number of SMS centers,

5. Back up mobile phone data (phone book, SMS, multimedia files, etc.). ) and restore the factory settings (Settings-Privacy-Restore Factory Settings). If you mean that the mobile phone can't send short messages, you can try to restart or replace the mobile phone to test whether there are any of the following situations: (1) The number of the short message center is set incorrectly, please re-enter the correct number of the short message center; (2) No signal or insufficient battery power; (3) The mobile phone shields the short message sending function;