Unlock/Downgrade thru Restore...Possible?

[tvoruz]

I have a 3GS iPhone 3.1.3 (5.12.01). I purchased the phone on 19 Feb 2010 and did a backup on itunes and then updated from 3.1.2 to 3.1.3.

My question: Is it possible to restore back to 3.1.2 using my backup from 19 Feb? If yes, will the firmware also revert, so it can be unlocked?

[madczech]

nope you can't unlock 5.12.01... doesnt matter if you did a itunes back up... on 3.1.2 you would have had to back up ur shsh file to be able to downgrade