No just need a sim im not a UK citizen so getting a contract wouldnt be possible plus im only there for a few weeks just need a sim for my unlocked 4S but 3 sounds pretty good as I wont be leaving the london area.The only cell phone co I know about is 3 havent heard about any others like Giffgaff at all and dont really know a whole lot about o2
So dumb question I just walk into a 3 store and ask for a sim whats the deal im new to this