Trawling the net, I have seen the question asked but not really answered convincingly.
I bought an iPad 3 32gb 4G (AT&T) in the USA recently. They fired it up in the Apple store and said everything would be fine using it back in the UK. I received a GiffGaff microsim, activated it, and the title bar of my iPad says 3G with good signal strength and the O2 logo next to it.
However, it doesn't work at all. I get messages saying that I have not subscribed to a data network and when exploring the settings menus, the iPad times out and says try later.
Some forums say that you must activate the AT&T sim in the US before bringing it to the UK but just as many people say this is not necessary.
Does anyone have experience of this? Have left help desk requests with GiffGaff but no answer, could take it into an Apple store if it is a hardware issue...
Thanks in advance of any assistance.