Oppo phones can't send short messages, but they can receive them.

① The network was busy at that time, so you can try to restart your mobile phone.

② Check whether other users around you have the same mobile phone usage.

③ If the mobile phones of the surrounding users are all normal, only their own ones can't be used, it is recommended to do a card replacement test to distinguish between the card problem and the mobile phone problem.

④ Confirm whether the SIM card is in arrears and stop the machine.

⑤ Check whether the number of SMS center has been changed (in Info-Settings-SMS Center Number).