This Guide is How to Jailbreak iPhone 3.1.2 Firmware using blackra1n RC3, Follow the simple step-by-step guide below to jailbreak all iPhone’s (2G/3G/3GS) and iPod touches (1G/2G/3G) on firmware 3.1.2.
Step 1: Download and install the latest version of iTunes if you haven’t already [Download iTunes
9.0.2 for Windows and Mac]
Step 2: Now you need to update/restore to the original iPhone OS firmware 3.1.2 on your iPhone by using the latest version of iTunes. Download iPhone 3.1.2 firmware [Download iPhone 3.1.2 firmware]
Step 3: Download blackra1n RC3 for Windows or Mac[Download blackra1n RC3]
Step 4: Start blackra1n app. If you are running it on Windows 7 or Vista, run the app with “Windows XP Compatibility” mode by right click on the app then click “Properties” then Choose "Windows XP Compatibility" that will avoid any errors during the jailbreak process.
Step 5: Click on “make it ra1n”:
Step 7: You should now have “blackra1n” in the list of applications on your iPhone. Run “blackra1n” app and select the packages you want to install like “Cydia”. This will jailbreak your iPhone or iPod touch on iPhone 3.1.2 firmware.
Step 8: Finally reboot your iPhone. Now You should now have fully jailbroken iPhone or iPod touch running on firmware 3.1.2.