OPPO A57s
Turn data roaming on or off
You can limit your data usage when abroad by turning off data roaming. You'll then not be able to access the internet using the mobile network when abroad. You can still use Wi-Fi even though data roaming is turned off.
Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press Mobile network.
Press the required SIM.
Press the indicator next to "Data roaming" to turn the function on or off.
If you turn on the function, press Turn On.
Press the Home key to return to the home screen.
1. 1. Find "Mobile network"
2. 2. Turn data roaming on or off
3. 3. Return to the home screen