I have found no satisfying answer to my problem. I understand a factory unlocked will work on any any American or foreign GSM network. However, I'm confused when it comes to Verizon/AT&T unlocked iPhones. So far, I have concluded that AT&T unlocked iPhone 4Ss are equivalent to the factory unlocked ones and will work on any American/non-American GSM network. However, Verizon unlocked iPhones will work on foreign GSM networks but they will only work on Verizon (CDMA) in the US. Is all of that correct? Anything else I should know? Also, is the Verizon unlock permanent? Thanks in advance.