This guide will not only show you how to update your iPhone 3G firmware 2.2.1 to 3.1.2 through iTunes. But, it will also show how to jailbreak and unlock your iPhone 3G on firmware 3.1.2 using redsn0w, pwnagetool and ultrasn0w. If your iPhone 3G is a non-official carrier set, this will be the guide for you to jailbreak and unlock while you’re performing iPhone OS 3.1.2 software update on your iPhone 3G.
Updating iPhone 3G firmware 2.2.1 to 3.0
This step is necessary to update the modem firmware 02.30.03 to 04.26.08 and the modem firmware will be updated when you’re updating your iPhone 3G to firmware 3.0. To update your iPhone 3G to a specific firmware version, download and save firmware 3.0 to your desktop and follow this step-by-step guide.
Please do not click the update button on iTunes as it’ll download and install the latest firmware version on your iPhone 3G.
Jailbreaking iPhone 3G firmware 3.0 using Redsn0w 0.8
After your iPhone 3G has updated to firmware 3.0, you’ll see slide for emergency screen. Now, download and save redsn0w 0.8 to your desktop and follow this step-by-step guide to jailbreak your iPhone 3G. Please check the modem firmware is 04.26.08 after your iPhone 3G has jailbroken.
Please do not unlock your iPhone 3G first after it has been jailbroken. We’ll unlock it later on this guide.
Creating 3.1.2 custom firmware for iPhone 3G
Here’s the fun part, we’re going to create the custom firmware. If you’re using Mac OS X, follow simonblog’s step-by-step guide, which will show you how to create 3.1.2 custom firmware using pwnagetool 3.1.4. If you do not have a Mac PC, you may want to ask your friend who is using Mac OS X to help you.
Restoring and Jailbreaking iPhone 3G with 3.1.2 custom firmware
Launch iTunes on your PC and shift restore your iPhone 3G with 3.1.2 custom firmware created. After restore is completed, your iPhone 3G is successfully jailbroken and you’ll find Cydia icon on the home screen. Please check your iPhone firmware version is 3.1.2 and modem firmware is 04.26.08 before we proceed to the next part of this guide.
If you’re getting error code 1600 from iTunes, make sure you’ve updated your iTunes to version 9.
Unlocking iPhone 3G using ultrasn0w 0.9
This is the last part of the guide, which is unlocking your iPhone 3G with the ultrasn0w unlock. Follow this step-by-step guide to install ultrasn0w 0.9 through Cydia installer. After that, insert the sim card into your iPhone 3G and you’ll see the name of your carrier on the status bar.
If you have any doubt in updating, jailbreaking and unlocking your iPhone 3G, feel free to leave your question on the comment below.