Some devices do not have data roaming automatically active, so if you would like to make use of mobile data whilst travelling abroad, you need to make sure that this setting is also activated from your device’s settings.
To activate data roaming from an Android device:
To activate data roaming from and iOS device:
If data roaming is ON, yet you still cannot use mobile data whilst abroad, you will need to check whether you are connected to the correct service provider.
If you are still unable to connect, check out this FAQ for further help.