Windows Users:(If you have mozilla firefox or Chrome, use that over Internet explorer! If you download the iPhone 3GS firmware (IPSW) through Internet explorer, watch this video how to turn firmware from .zip to .ipsw, we need it as a .ipsw!)
Mac Users: Make sure you turn off "Open safe files after downloading" before you download the firmware, by going to Safari (upper left hand corner) then preferences, then uncheck the "Open safe files after downloading".
If kittyra1n helped you jailbreak and unlock your iPhone 3G, feel free to like kittyra1n on facebook, follow kittyra1n on twitter, and feel free to donate ANY amount.
If you ran into any redsn0w errors, such as getting stuck on "uploading Ramdisk", Click here.
Jailbreak and unlock iPhone 3G 4.2.1 firmware untethered for free with redsn0w. This will work on Microsoft Windows and Mac. This is similar to greenpois0n, blackra1n, and limera1n. After the unlock you will be able to use your iPhone 3G on any carrier, such as AT&T or T-Mobile.
The jailbreak and unlock won't affect your exisiting AT&T wireless service. This jailbreak is untethered, this is a good thing. While technically Apple considers jailbreaking voiding the one year warranty, all you have to do is restore in iTunes and your iPhone will be back in warranty, this goes the same for insurance.
Download and save Redsn0wRedsn0w for Windows
Download and save iPhone 3G Firmware 4.2.1 IPSW
(You should download the firmware through firefox, if you download it through IE, change the extension from .zip to .ipsw, if you download the firmware through Safari, before you start the download go to Safari in the upper left hand corner, click "Preferences" and uncheck "Open safe files after downloading")
If you downloaded it through Internet Explorer, heres how to change the .zip into .ipsw
Once all the downloads are done, go to the folder where all the files you downloaded are located at, most likely your "downloads" folder on your computer, you can also go to this by right clicking redsn0w and click "Open containing folder"
If you are on Windows Vista or Windows 7, right click redsn0w and click "Run as Administator", if you are using XP, or Mac, you do not need to do this step, just open it normally.
IF your computer asks are you sure you want to open this file, say Yes
Once redsn0w is open, click browse, we are going to browse for the other file we downloaded, the iPhone 3G 4.2.1 firmware.
Find and choose the iPhone 3G 4.2.1 IPSW firmware, it should be in your downloads folder, but it could be somewhere else, if redsn0w isnt recognizing it, you need to download the ipsw again through firefox, and choose that one.
Once redsn0w successfully recognizes the iPhone 3G 4.2.1 IPSW, press next
Choose "Install Cydia" and "install iPad baseband", I suggest you uncheck "enable multitasking" because it will slow down your 3G dramatically. You can leave "enable homescreen wallpaper" and "enable battery percentage" checked if you want.
Now make sure your iPhone is plugged in, if it is, turn it off. Before you press next, you will have to put your iPhone 3G into a special mode, a mode called DFU mode, essentially you hold the power button for 3 seconds, once you see the Apple logo come up, hold down the home button at the same time as you're holding the top button for 10 seconds, after 10 seconds, let go off the top button but keep holding the home button for 10 more seconds!Your iPhone 3G screen should now be blank, if it is blank, press next, if it isn't try DFU mode again, if you need help watch this video.
Ignore any messages from iTunes, DO NOT RESTORE IT NOW, now that your iPhone 3G is in DFU mode, press next on redsn0w, this will jailbreak and unlock your iPhone, leave it plugged in until it finishes.
Your iPhone will now boot back up, you will notice a new icon, Cydia. Before you open Cydia on your iPhone, connect to wifi, by going to Settings, Wifi, and choose a wifi network to connect to.
Now open Cydia, it will load data, it could take a few minutes, and it might restart a few times, this is normal. When it asks if you are a "user" "developer" or "hacker", choose "user".
IF it asks you about upgrades, choose "complete upgrade". Any errors cydia might give you is normal. After the upgrades you might need to restart your iPhone, if does, restart it, and then open up Cydia again.
Now open Cydia again, and at the bottom right, tap "search" and search for ultrasn0w. Then tap on it, and press install at the top right, then press confirm.
It should say you need to reboot your iPhone now, if it doesn't turn it off then turn it back on.
You can now insert any sim card into your iPhone 3G, if you don't get a connection right away, turn your iPhone off then turn it back on.
If you ran into any errors, such as stuck on uploading ram disk, check this video on how to fix it, then run redsn0w again.
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