How-to Unlock 3.1.3 Firmware 05.12.01 baseband using ultrasn0w
Now, you can unlock iPhone with 3.1.3 firmware installed and 05.12.01 baseband version, also unlock 05.13.04 baseband by using ultrasn0w 0.93.
If your iPhone is a factory unlock (FU) one, you do NOT need to unlock your iPhone, because it’s already unlocked 🙂
You need to jailbreak your iPhone before you can unlock it. Read this tutorial to jailbreak iPhone 3.1.3 firmware (using redsn0w 0.9.4): Jailbreak iPhone 3.1.3 Firmware
The baseband version of iPhone 3.1.3 firmware is 05.12.01. Now, you can unlock 05.12.01 or 05.13.04 baseband by using ultrasn0w 0.93. Check your baseband version and make sure the baseband version is 05.12.01 or 05.13.04 before you continue reading this guide.
Don’t forget to install cydia while jailbreaking your iPhone. Add repository to cydia: repo666.ultrasn0w.com and then install ultrasn0w 0.93. Wait for few minutes, then you will have an unlocked iPhone.