OPPO A77 5G
Android 12.0
1 Find "Fixed dialling numbers"
Press the call icon.
Press the menu icon.
Press Settings.
Press Calling accounts.
Press Advanced settings.
Press Fixed dialling numbers.
2 Turn on fixed dialling
Press Enable FDN.
Key in the PIN2 and press the confirm icon.
3 Turn off fixed dialling
Press Disable FDN.
Key in the PIN2 and press the confirm icon.
4 Return to the home screen
Press the Home key to return to the home screen.