OPPO Reno 5G
It's not possible to send and receive text messages
Solution 2 of 3: The message centre number is incorrect
A text message is a message that can be sent to other mobile phones. Your phone can send and receive text messages as soon as you've inserted your SIM. If this isn't the case, you can set up your phone for text messaging manually.
Press the message icon.
Press the settings icon.
Press More Message Settings.
Press Message centre.
Key in +447958879879 and press the confirm icon.
Press the Home key to return to the home screen.