I have a two years old iPhone G3 which I just upgrade iPhone4. AT&T turn off activity 3G and switch over new activity new iPhone4. I want to give my old G3 to my son which I can afford the different cell phone carrier than very expensive AT&T carrier. My question is do I really have to do JB to remove the AT&T information in this 3G? The guy at store said that I have to remove information of AT&T first. He suggest do the JB. Will iTune work this way with JB? Can it be update the operating system 4.0 and other apps with iTune update or download pay or free apps and etc.? Any body please explain how this work or instruction and save me the trouble at end. I appreciated your big help and feedback.