iphone 3gs sim card not inserted and no service

[steve99750]

hi guys

i've recently i bought a 3gs that was on a o2 network in the uk,i have put my sim card in to activate the phone as the previous owner did a factory reset on it so it was fresh when i received it,when i plug the usb lead in itunes says there is no sim card inserted and alsoit says no service on the phone itself,theres nothing i can do as itunes wont recognise my phone and its stuck in activation mode.please help