Forgive the seemingly dumb question (or maybe it really is dumb, I don't know), but what exactly uses the iPhone's data plan when it's connected to WiFi? And no, I'm not talking about calls and texts; I know those are data -- not WiFi transmissions, and they are reported as calls and texts anyway. I know voicemails are data usage and are not ever routed through WiFi. The reason I ask is that after all this mess about the new data plans, I've paid close attention to my data usage in just the last two days to see exactly what activities use how much data. There are 4 items billed as data usage when I was definitely on WiFi and should not have had any of the iPhone's data being used. There were no voicemails being left or retrieved at those times and for the life of me, I can't figure out what that data usage is for. Any ideas? What sort of apps or whatever else would go through the data network instead of WiFi?