I bought my Iphone 4 about 3 months ago at an AT&T store in California. However, since I live most of the time in Mexico, and was returning to Mexico imminently, I immediately substituted a different phone to be under the contract and took home the Iphone to be used without a SIM card, more or less as a glorified Ipod. I intend to go back to AT&T when I return to the U.S. and will get a SIM card installed for the phone. The SIM-less Iphone has been working fine up until now without a SIM card. I have many apps and have used the wifi extensively. A couple of months ago I even updated the Iphone to a new operating system, and was able to continue using the Iphone. However, today I decided to upgrade to the latest Iphone operating system. I backed up my phone first using Itunes, and then upgraded. However, now my phone only displays a message which says "No SIM card installed. Insert a valid SIM with no PIN lock to activiate IPhone." If I slide the "slide for emergency", I get the keypad allowing me to make an emergency phone call. I can't seem to get beyond this screen. Even though my apps are backed up on Itunes, the Itunes software just displays a message also saying "There is no SIM card installed ...", and I don't have an option to restore the apps from what I had previously backed up. I am in Mexico and am not near an AT&T store. Is there a way that I can get past this screen, restore my apps to the phone, and use it for its wifi capabilities while out of the U.S?