So right now I have a plain old At&t phone and am part of a family plan. The main phone on the plan is my mom's iPhone. I got it only about 3 weeks ago, and today I talked to an At&t worker on the phone and he said that if I wanted to have an iPhone on that plan, I would need to pay only $30 more per month than I am paying now. This got me interested in buying an iPhone 3g. My question is how would I go about changing my phone to an iPhone, and would I need to deactivate my current At&t account?