after I tried method 2 and I couldn't unlock it I flashed MK2 modem back and now my phone tripping and keep freezing please I need help just to get my phone work normal
here's pic for my phone information now[/QUOTE]
Greetings. I achieved my sgs4 unlock sgh-I337 in 4.4.2 but lowering the modem to mdl. but then again I had to flash the stock rom 4.4.2 to return the modem up. but I did going into safe mode with * # 0011 #
(1) *#0011# (found working on AT&T Galaxy S4)
(2)Now select  UMTS by tapping on it.
(3)When you get into the UMTS Main Menu, tap on  DEBUG SCREEN
(4)This will take you to Debug Screen menu where you have to select  PHONE CONTROL
(5)In the Phone Control menu, you will see an option called  NETWORK LOCK. Tap on it
(6)In the Network Lock screen, select  PERSO SHA256 OFF.
(7)On the next screen tap on SHA256_ENABLED_FLAG.
(8)Doing this will show the following message:
MENU NOT EXIST
PRESS BACK KEY
Current Command is 116631
(9)Now tap on the Menu button (left soft key on your phone) and select Back from the menu. (To go back, do not press the Back button of your device.) When you do this, you should see the following lines on the screen:
SHA256_OFF => Not Change
(10)Ignore the above message and tap on the Menu button again and then select Back.
(11)Now you’ll see the Network Lock menu. Press the Menu button again and select Back. Repeat the Menu> Back action till you return back to the UMTS Main Menu.
(12)Here you will find an option called  COMMON. Tap on it.
(13)Next, select  NV REBUILD.
(14)In the NV Rebuild screen will look like as shown below.
You can Restore Cal/NV
(15)Tap on  Restore Back-up.
(16)Doing this will freeze your T-Mobile/AT&T Galaxy S4 temporarily. The screen will turn Off , followed by the Menu and Back buttons light up and device reboot.
this method worked lowering my modem to MDL, but then I had to flash the stock rom again to raise your version NB1 modem because I found not only the NB1 modem to flash it with odin. good luck and I hope you help