I have an iPhone unlocked with IPSF running software version 1.0.2 with modem firmware 03.14.08_G. I recently changed to AT&T iPhone service and want to just restore factory setting and run 1.1.3 and have a legit phone. Is it safe for me to do so? I checked and my IMEI number is still the same as the one that is on the box if that has any effect.