Why can't the mobile phone send short messages, even if it is mobile Unicom?

According to the situation you described, the possible reasons for not sending text messages and how to deal with them:

1, no signal or insufficient power;

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

3. The SMS inbox and sending box are full;

4. Try to restart or replace the mobile phone for testing;

5. Query whether the SMS function is turned on.

If the above situation has not been solved, it is suggested that you can contact the local manual customer service for handling.