Need clarification to downgrade firmware for 3GS
I have been following all the threads and postings on iclarified regarding unlock/jailbrea.
From what I understand so far, 3G and 3GS that have been upgraded to Version 3.1.3 with Firmware 05.12.01, currently there is NO WAY to unlock, only jailbreak.
However, there is posting on iclarified to downgrade firmware to an earlier version (assuming the phone has been previously jailbroken and unlocked before).
iClarified - iPhone - How to Downgrade Your iPhone 3GS Using a Cydia Saved SHSH [Mac]
Does it really mean one can downgrade firmware from 05.12.01 back to 05.11.07, thereby making this possible to unlock?
Would someone please clarify this.