I bought a second hand iPhone 3g, with iOS 3 something, it was jailbroken. I wanted to update it to 4.2.1, I thougth that using the update feature on itunes I would be able to update it, and later jailbreak it. But when I did the update, it got stuck with the following message on iTunes: "The sim card inserted in this iphone does not appear to be supported". I'd tried to use redsn0w to jailbreak it and unlock it, but it never finish the jailbreak, it's supposed to show a lot of text messages on the screen after rebooting, but it doesn't. Any other unlock solution depends on using cydia or some other tool, but I can't get past the screen of USB connecting to iTunes. By the way I can't get the original sim card of the phone, i don't even know for which country. I really need help to fix this.