I got an iPhone 3G off of CraigsList, and I'm planning on switching my family and myself over from Verizon to AT&T. From my understanding, it's possible to get around the required $30/month data plan by purchasing a phone from AT&T ("dummy phone"), then putting that SIM card into my iPhone. To do this, I would need to jailbreak (but not unlock) my iPhone, correct? Also, what would happen if I were to purchase a data plan for my "dummy phone"? With unlimited messaging on a family plan, data for one for is $10/month. Would this be compatible with my iPhone?