Here's how to easily unlock you GS3 or Note 2 on JB (nothing needed but your phone).

[Timzer]

Ok this is as easy as it gets. If your on Jellybean, these are the simple steps to unlock your phone.

Before doing the instructions below, make sure you are indeed locked.
Note: your phone must be running at least Jelly Bean 4.1

AS USUAL: Do this procedure AT YOUR OWN RISK

Step 1: Launch the phone app and press these keys: *#197328640#

Step 2: From the Main Menu, navigate to [1] UMTS > [1]Debug Screen > [8] Phone Control > [6] Network Lock > Options.

Step 3: In the Options screen, choose [3] Perso SHA256 OFF. Wait for 30 seconds after making this selection.

Step 4: Go back one step by pressing the menu key, and then back once. You should now again be in [6] Network Lock

Step 5: Here, now choose [4]NW Lock NV Data INITIALLIZ. Wait for one minute after making the choice.

Step 6: After a minute has passed, reboot your GS3 or Galaxy Note II.


Source

 

[KnightMan]

Worked! I cannot believe it was that easy. Are all android phones this easy to unlock? I'm on month to month, so now I'm free to just pick up any sim I want. SWEEEEET!

 

[DanteMann]

First the wicked new software update, now this. Wow, I'm really shocked at the ease of this. The GS3 experience just keeps getting better and better. Cannot wait for the GS4!!! 5 inches, 1080P, 441 PPI, One Quad Core Exynos Chip for all, and one GS4 for all. WOOOOHOOOOO!!!!!

 

[aziatiklover]

Is this a permanent unlocked? Will it lock if the next firmware comes out?

 

[F123D]

Wow, thanks for the tip and link. Don't need to unlock but great to know that it's there and easy to do.