Redsn0w is yet another unlocking and jailbreaking solution for iPhone and iPod users. It can jailbreak and unlock OS versions 3.1.2 and 3.0. All iPhones and iPod touch are supported except the iPod touch 3G. For the late 3GS models and iPod Touch MC models, the process is still tethered. Here is a step by step guide to unlock and jailbreak iPhone 3.1.2 using redsn0w 0.9:
1. Download iPhone 3.1.2 firmware using direct download links posted here.
3. Open up iTunes. It’ll detect your iPhone.
4. Press Shift and click restore. Browse for the ipsw file you downloaded in step 1. iTunes will restore the iPhone to 3.1.2. Let it do its work. It may take some time.
5. Open redsnow (redsn0w). Browse for the ipsw file you downloaded in step1. It’ll verify the file. Click next.
6. Check “Install Cydia”. Also check “Unlock” if you want to unlock your iPhone. Click Next.
7. Download 3.9 and 4.6 bootloaders from here and specify their locations. Click Next.
Voila, You’ve just unlocked and jailbreaked iPhone 3.1.2 using redsn0w 0.9. Enjoy