I have had an iphone 3g for around 15 months now, decided to upgrade to the iphone 4 and i gave my sister the iphone 3g. I had this phone unblocked with o2 so that i could use my virgin sim card in it. Has worked fine all the time, but today when we went to put my sisters t-mobile sim card in the phone it just says no sim. And if i then put my virgin sim in it, it works straight away 
Anyone have any idea what to do?
Anyone have any idea what to do?
