I have a grandfathered ATT unlimited data plan and am using an iPhone 5. My wife and mother-in-law are also on this plan with "dumb phones" and we share minutes. My wife is thinking about finally making the jump to a smart phone and I'm just wondering what people experienced regarding their data plans. Were you forced onto a shared data plan or was it possible (and economically viable) to retain the unlimited data and simply add a separate phone and data plan onto it? Thanks for any input you can provide. My research on ATT's website isn't yielding much that looks desirable to me.