I can't use my phone's internet connection

Data roaming is turned off

Turn on data roaming.

1 of 6 steps Press Settings.
2 of 6 steps Press Mobile Data.
3 of 6 steps Press Mobile Data Options.
4 of 6 steps Press the indicator next to "Data Roaming" to turn the function on or off.
5 of 6 steps Press the Home key to return to the home screen.