I have an easy question. I asked it before but didn't get many comments. I have 2 iphones in a family plan. I do have data service on my line and everything seems fine, whereas in wife's line, there is no data plan added, basically we are paying only for one data plan for two iphones. My wife uses her phone at places she has free wifi all the time, so can we keep it this way as long as we want? Or will AT&T tell us "ohhh, sorry guys, we forgot the charge you for data plan XX months, here is the new bill" ? What would you do if you were in my shoes?