Unlock iPhone 4s Question

[yof]

I have an iPhone 4s bought it unlocked and it's with at&t plan. But I'm going to the Uk soon and I wanted to know if I can use it with them (o2) with their plan. Do I have to restore my iPhone 4s to switch carrier? Or is the sim card plug and play and I don't have to restore? I searched for the answer but I couldn't find anything.

[Ads]

[dbcv]

If your phone is factory unlocked then you can use it on any carrier anywhere in the world.

[Unleashed]

ATT do unlocks now so contact them and ask them if you are eligible for unlocks and you can then use it with o2

[fmirzamd]

If you bought unlock then you can use any Sim card. When you go to UK just put new Sim card and you are ready to go.
No need to talk to ATT.

[Unleashed]

If you bought unlock then you can use any Sim card. When you go to UK just put new Sim card and you are ready to go.
No need to talk to ATT.

firstly NEVER pay for unlock unless its using a gevey sim but ATT would permanently unlock it where as these unlock methods would only work for certain basebands and lock up again if you try upgrade firmware.. it really does not make sense to me why any one would chose that over an official unlock

[yof]

thanks all I'm planning to get the next iphone 5 unlocked !