Launch redsn0w 0.9.6b5 ( for windows seven use compatibility mode to windows xp ) and select the ipsw firmware 4.2.1 file and wait for redsn0w to identify the firmware.
Find out more about unlocking your i Phone 3G for free below.
So for those of you that have to worry about new bootroms (i Boot), new bootloaders, et cetera, I am most likely not on the same upgrade path as you.
I also do not have the ability to purchase an i Phone for every possible permutation of upgrade path out there to document it.
If you choose to use either your network, or a third party provider, don’t forget to tell us how you found the service in the comments section, as this helps others select a service in the future.
Unlock the i Phone 3G yourself for free If you have an i Phone 3G it is pretty easy to unlock for free.
From the next options list, select Install Cydia and Install i Pad baseband options and click next.