They were beautiful are the days when you could do after the jailbreak and unlock iPhone software with the most ‘powerful and easy to use as blackra1n.
However, for those who have older versions of firmware up to 3.1.3 can ‘still use it.
I remember how to use Blackra1n:
End! You can enjoy your device updated, unlocked and jailbroken with the latest available firmware and Cydia. The whole process, even counting the time for a restart of the device, takes about 30 seconds!