i have a note 2 from US cellular in the US which is CDMA. im traveling to Paris (currently in paris now) and i bought a new Note 2 that runs on GSM. now my problem is that the phone is carrier locked to a korean phone company. I posted this in the ATT section because i could not find a section for my phone model and many of my close solutions referred to using ATT firmwares so i felt this was the closest section.
my phone info:
Galaxy note 2
Android version: 4.1.2
Device status: normal (unrooted) (i have my US cellular note 2 rooted through one button method and can probably do that to this phone as well if needed, so if you have a solution that contains root access please know i can still go that route!)
so to carrier unlock this phone i read about this easy method:
Step 1: On your Galaxy Note II, launch the phone app and press these keys:
Step 2: From the Main Menu, navigate to  UMTS > Debug Screen >  Phone Control >  Network Lock > Options.
Step 3: In the Options screen, choose  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  Network Lock
Step 5: Here, now choose NW Lock NV Data INITIALLIZ. Wait for one minute after making the choice.
Step 6: After a minute has passed, reboot your Galaxy Note II.
but my problem is that when i enter that first code i get this message: "connection problem or invalid MMI code."
so i searched how to resolve that. i found some threads saying that i need to downgrade my firmware to 4.1.1 because 4.1.2 blocks this on some phones. so i looked into downgrading my firmware. Went to samsung-updates and entered my device model and they only had 4.1.2 firmwares. i didnt try an ATT firmware because im not confident it will work so if i can get assurance that it will ill try that route.
from there i also googled my model and firmware 4.1.1 and found nothing.
somewhere in all this i also was told to change my csc as well. I tried doing that with the code provided online and received the same error message. i would like to change the csc so it runs on UK csc as well.
sorry if anything is confusing, im not a huge tech guy when it comes to phones, but i try. I dont know how to flash roms or anything, only reason i ever rooted a phone was to use free tethering.
in conclusion, i just simply want to carrier unlock this korean note 2.
any help is appreciated as i would like to get a phone plan here in france asap but i want to make sure this phone is going to work. I dont even know how to check if its carrier unlocked after i do succeed in this. i have access to a tmobile sim card if needed to check.
thanks in advance and thanks to everyone who has helped others on this site. i have used your expertise many times in the last few years and now finally i can say thanks for the great information!