Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A405 Safari/7534.48.3) This issue is driving me batty lately. My wife never leaves the house yet she's burned through her entire data allowance in 1 week. Even my Phone is using massive amounts of 3G data while I'm at home and connected to wifi. I've turned off nearly every feature we can think of that may be causing it but still we see 3G data usage when wifi is connected. Siri and iMessage appear to use 3G no matter what unless you turn off cellular data altogether. Only then will wifi be used. To test this, connect to wifi, reset cellular usage stats, ask Siri to send a text (to someone that is iMessage), send the message and recheck cellular usage. Voila, about 17KB used. Even if Siri and iMessage always use cell data - I'm pretty much fine with that since it's small amounts - there is something that uses massive amounts. Like 20mb to 130mb each evening. I have a feeling that app updates occur over 3G too, but not convinced yet. I've disabled iCloud features to the point where it's almost useless and still no luck. At the rate we are going we will both fly through our data for the month. Anyone else resolve this? Ideas? I have a genius bar appt this am but I'm pretty sure they can't help me, but we'll see.