The Real Way to Unlock your iPhone 3G 4.2.1
I own an old iPhone 3G. I don't use it much anymore, but I decided that it was time to unlock the phone so I could use it for things like international travel or just a nice iPod if i wanted to. That lead me to jailbreaking my iPhone. My main purpose for doing this was to unlock the SIM card for international use. But jailbreaking the iPhone is a perfect way to bring new life into an old device.
Yesterday I set out on my quest. A quick google search on "jailbreak iPhone" turns up various results. Some are quite old (2007) and thus completely useless, but others were quite new and I'd learn were equally useless because the programs would only work with the latest firmware Apple has out. As you may know the iPhone 3G tops out at 4.2.1. That means I cannot run the latest firmware (note that the 3GS can be upgraded to the latest firmware).
That lead me to a new google search. "Jailbreak iPhone 3G 4.2.1." This, it would turn out, was also useless. It lead me to a program that everyone raved about called Greenpois0n. The program sounded awesome and the pages I hit specifically said it would crack the iPhone 3G running 4.2.1. But after trying to use it and failing, and reading comments of people in the same plight I gave up. I did find a couple of comments referencing something called RedSn0w. RedSn0w looked like the perfect choice, but while trying to unlock my iPhone it wouldn't recognize my ipsw file.
It was at this point that in frustration I tweeted the following:
I'm trying to jailbreak my old iPhone 3G running 4.2.1. So far nothing seems to be working. Anyone had success recently?
I still haven't gotten an answer from that. But I decided to check out Greenpois0n again. They have an IRC channel. So I got on there and finally got my answer. It turns out that you need a specific version of RedSn0w. Not just any version will do. The user pointed me to the following mirror with the correct software that worked for me. Apparently I needed 0.9.6b4.zip. Once I installed that and ran it it it immediately recognized my ipsw file (located ~/Library/iTunes/iPhone Software Updates/) From there it is pretty simple and straight forward what you need to do via the program instructions. You hold the power button for a bit then add the home button then take away the power button and wait. Suddenly your phone will reboot and you'll be in business. If you start seeing strange text flowing on your black screen you've won. You beat Apple.
I have no idea why later versions or different versions of the same software wouldn't work with my ipsw file. None of them seemed to recognize it. But this specific version of this specific software did work. And once it did it took me less than 20 minutes to hack my iPhone. So I'm sharing this information so that you don't have to waist the same amount of time I did hunting this info down. Since the iPhone 3G cannot upgrade anymore this method should work until iPhones are in museums.
In case the link above to the RedSn0w software disappears.