Oppo mobile phone always fails to send messages, and the sending failure has been saved to the outbox. What is the explanation?

The processing method that the mobile phone cannot send short messages is as follows:

First, you can change your mobile phone and see if you can send and receive text messages;

Second, if you can send and receive short messages, I suggest you plug the card back into your mobile phone and send yourself a short message to see if you can receive it.

Third, if not, I suggest you check whether there is a problem with the sim card.

4. Check whether the number of the SMS center is set correctly;

5. Bring the mobile phone card to the local business hall for testing or replacement.