[AT&T Samsung Galaxy S 4 General] bvzxa3:
UPDATED 7.14.2014

Method 1 (rooted)

The easiest way you can use RegionLockAway for those on MK2 is to do this:

I did this on the stock MK2 ROM stock.

Since no one either bothered to look in the same forum for the modem thread here is a link to the modems:

http://xdaforums.com/showthread.php?t=2496517

1. Root the phone on

Stock

MK2.

2. Download and install Safestrap.

3. Download MF3 modem.

4. Install the modem using Safestrap from the stock rom slot (what I did)

5. Reboot the phone, go to settings, and confirm you are on the MF3 modem. (this will not affect KNOX or bootloader)

6. Run RegionLockAway 1.3

7. Shut the phone down and insert any other carrier sim and turn the phone on, or leave the sim in after installing the MF3 modem, bypass the code unlock screen and then run RegionLockAway 1.3

8. Reboot and you should see it activate your carrier.

9. You can also flash back to MK2 if you like. (optional)

I can confirm it worked and the T-Mobile sim was accepted. There was no invalid sim prompt or unlock code prompt after doing this. I even flashed back to the MK2 modem and it still stayed unlocked.

Unfortunately the person I got the phone from had reported it stolen and when it went to activate on T-mobile is threw up the MM#6 code meaning the phone can't be activated due to bad IMEI. Apparently the guy who sold it to me assured me it would work on AT&T and everything was good. I had the phone maybe 5 days and after unlocking it later found out he reported it stolen. So yes I got scammed. Luckily I only paid $100 for the AT&T GS4. However for being honest on craigslist that I had a beautiful AT&T GS4 with Bad IMEI I was able to get $250 for the phone from a guy who fixes these problems...and that's all I will say to that. So now I have a Galaxy Note 1.

For those on KitKat 4.4 NB1 Here is more info from DroidDonX

Link is at the bottom of the post!!

Method 2 (posted by

muniz_ri

)

Alternatively, I337 owners can flash the MDL modem via Odin to re-gain access to the hidden menu(links to signed, odin flashable modems below) then follow the guide in the OP to unlock your phone. Once completed you can re-flash the MK2 modem. I tested this process on my own stock i337 running stock MK2 and it works but follow at your own risk. Also, my knox warranty flag has been tripped for a long time so I don't know if flashing the MDL modem will trip the flag or not. Someone else can chime in on that. Cheers:

MDL Modem: https://mega.co.nz/#!wpUUXQCS!Aws3S1HWW31WUnA1s4BavFsyoNU7fBTVaEvIzcd3t6M

MK2 Modem: https://mega.co.nz/#!pwESna5I!YK7EKG37xXIG1ReB-Z-mfSMoXNkXQ9t2EdMK9ofgJKg[/QUOTE]

To finish this method go to this thread:

http://xdaforums.com/showthread.php?t=2285431

*muniz_ri has stated he is not sure whether this will trip KNOX or not*

**Method 2 has been confirmed to

not

trip KNOX by users**

Thanks to RockRatt and deadlysin9 for letting me know it was safe to just flash modems while on MK2 rooted

My method to root the AT&T S4 was saferoot

http://xdaforums.com/showthread.php?t=2565758

For those who need to downgrade from 4.4.2 to 4.3

Method 3 (For those on NC1 or higher) [MENTION=5934777]NewToGalaxy[/MENTION]

Link for the files needed:

https://www.dropbox.com/s/16fu4havwvbt59c/NC1unlock.zip

Disclaimer

I am not responsible if you brick your phone. You should have some working knowledge about your phone as well as rooting and flasing. This is not a comprehensive guide. This is a workaround for those on MK2 firmware where in none of the secret codes to access the SIM lock will work.