I bought the unlocked Nexus One a couple months after it came out, I was already on T-Mobile so I just inserted my sim and I was good. Well sometimes I get frustrated with T-Mobile's spotty 3g. So I thought about switching to ATT but I was told I can't because I need an ATT version phone. Well I just checked my mobile networks in settings and it gives me the option to register to T-Mobile or ATT. Obviously I can't use ATT cause I'm not with them but does this mean I can actually switch to ATT?