I have an iphone 3gs with 4.3.3 firmware and a baseband of 05.16.02. I jailbroke with jailbreakme.com then I downloaded ultrasn0w through cydia and had it unlock my phone. However now, I cannot connect to At&t 3g. I am planning to switch my sim card in the near future to a different carrier. Is the only way to do this is by upgrading to the ipad baseband? Or did I do something wrong with the way I unlocked (I just let ultrasn0w run on the phone).