I purchase an iPhone 3g a while ago on ebay.It worked fine even though I had no sim card. Yesterday I updated to iOS4 but it says "there is no sim card on the iPhone you are attempting to activate".My question is do I need an at&t sim card to activate? I have a tmobile sim card on my Blackberry.If I insert the sim card to the iPhone would it work? Im not planning on using the phone I just want to use the iPod and the wifi... Thanks in advance..