To enable your device for mobile data while out and about using your Network Providers plan, simply follow the steps below:
1. Go to Settings, and then select SIM Cards, afterwards, press the SIM Card you would like to access the data for.
2. Now swipe down from the top of your screen twice. You will see a small, right angled triangle labelled "Mobile Data". Simply tap that and select "Okay" to activate!
You will know if it is active by the small 3G or 4G symbol in the top bar of your device.