I have been bad with IPhones. I have a blackberry curve through AT&T. I have unlimited messages and Internet. I bought an iPhone 3GS off eBay. I'm a gluten for punishment I guess. It looks brand new. It was on AT&T. I put my sim in it turned it on and I can make calls and send receive texts. I can even get picture messages. On the top left it says AT&T. I can go to the Internet and says no cellular data. I haven't synced to I tunes. I'm new and need help. I have searched and found to reset network settings it didn't work. What do I need to do to resolve it? Thanks for all the help.