I looked and looked, but couldn't find the answer to my particular situation. Ok so, I had an AT&T phone with voice and $5 sms, no data. I bought a used iPhone 3G off craigslist. I've been using it unlocked fine for 1/2 a month now, but there's problems with jailbreaking/unlocking and the phone seems to lag. so, I this is what I want to know: Is it possible to restore the phone, just put my at&t no data sim in there, and have it work? ps: i had accidentally restored the iphone once with the sim in there, and it said "iPhone activated" or something like that. And the iPhone shows up on at&t's website as my phone, but no data plan automatically added or warning texts yet.