I've been monitoring my usage on my 4S with AT&T. Somewhere between 11:30 and 12:00 (a lot of time, right at 11:49pm) there always seems to be anywhere from a few megabytes to 75MB sent every night. Funny thing is I'm on WiFi when I'm home. AT&T usage only shows data that was sent over 3G. Right? Over 30 days, this could add up. I went back and looked at my previous bills with the iPhone 4 and same thing. So what is the phone doing?