Sony Xperia 10
Turning 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 Network & Internet.
Press Mobile network.
Press the indicator next to "Roaming" to turn the function on or off.
If you turn on data roaming, press OK.
Press the Home key to return to the home screen.