From the Home screen, swipe up to view your apps.
Scroll to Settings.
Tap Settings
Tap Wi-Fi and internet.
Tap SIM & network.
Tap SIM 1.
Tap or slide the Roaming switch to ON.
Turning data roaming on allows you to connect to data services while roaming. Turn data roaming off to keep from incurring significant charges.
Tap OK.
You've completed the steps!
