I don't have an S3, and I'm not exactly sure about your "background data", but on a Jelly Bean device you might want to check:
Menu > System Settings > Data Usage. Then look at "Mobile Data" and make sure the toggle is "ON".
I don't have an S3, and I'm not exactly sure about your "background data", but on a Jelly Bean device you might want to check:
Menu > System Settings > Data Usage. Then look at "Mobile Data" and make sure the toggle is "ON".