i'm helping a friend upgrade her 3.1.2 3GS phone to iOS4 and i'm just trying to find out as much info as possible before i begin. she's currently running on T-mobile so her phone is def. unlocked but i don't see cydia installed. i'm wondering if her phone was factory unlocked, she received it in taiwan as a gift. if it is factory unlocked, does doing a straight upgrade to ios4 end up locking her phone, or should i use the same pwnage custom build i used for my att 3GS to upgrade to ios4? thanks.