My iphone is somewhat of a special case. It was purchased through AT&T and it has always been locked to them. However, I replaced it while in Singapore and the phone they returned to me is unlocked. I restored the phone and it locked it once again - I guess since the Apple servers paired it to my AT&T account. I have replaced the phone again in Singapore and once again I have received an unlocked phone. My guess is - if I restore it, Apple will once again pair it to my AT&T account and lock it. Anyway, I want to update it to iOS 5.1, but I know once I do it will lock it again. However, before I "restored" it. Once I restored it, it came to the "connect to iTunes" to activate the SIM and reported invalid SIM. My question is: if I click "Check for Update" instead of "Restore", will it still end up in the "connect to iTunes" state or will it simply update the software without restoring. bottom line, will "check for update" lock my phone?