I followed the Instructions listed here to get a gophone SIM card working with the iphone. I even restored the iPhone 3GS with the SIM card in it and reset network settings. It is an orange/white SIM card, and I currently have the cheapo phone on the really cheap 10¢ minute plan (only using this to make sure it can get an AT&T signal. Strangely when booting up, it said "Searching..." then just said "No Signal." I did get this used off of craigslist but the original owner never mentioned that the cell radio didn't work. I've also tried a T-Mobile SIMcard in the device (not unlocked). Any ideas on how to get it to work? It is running iOS 5.1 with modem firmware 05.16.05, possibly able to downgrade to IOS 5.0.1, or upgrading the firmware if it's not unlockable.