Hello, I have ordered a micro sim from giffgaff. My iPhone 4 is currently with tesco. I read that although they use the O2 network, giffgaff sims do not always work in them if they are still locked. I just tried it and it said searching and then said O2-UK and had 3 bars of signal. So does that mean that it works in my iPhone? Obviously I cant actually do anything as I haven't activated it yet. But with the signal and it saying O2-UK does that mean I don' t have to bother getting it unlocked?