[Samsung Galaxy S8 Guides, News, & Discussion] Nexii5:
Everything on my phone is working at full capacity as far as I can tell. VoLTE, WiFi Calling, Band 12, Video Calling, HD Voice etc...

I don't have time yet to do a complete guide but I'll post some of my thought below each step posted below.

How to change carrier:

1. Download Factory Binary, EngBoot, and the G950W firmware. (i dont think engboot is needed i did it without eng boot and works) - These files can be found on sammobile or updato and in many threads on these forums. Just make sure you get the right version (s8 vs s8+). They'll be zip files so you'll need something to open them, I used a free trial of winzip but I heard 7zip works fine too. The factory binary file I downloaded and used was called Combination something or other.

2. Turn off phone

3. Hold down on Bixby button + power + volume down

4. open Odin v3.12.7 - This is pretty easy to find too. Just google it. It's the latest unmodded version I believe.

5. add the Factory Binary to the AP section of Odin. - If for some reason you open odin and try to add the zip file to the AP section and it isn't showing up as a valid file, then unzip the file and try looking in the unzipped file.

6. Plug your phone into your computer (NEEDS TO BE WINDOWS) with Odin open it will say added or something in Odin, it's pretty obvious it's connected

7. Make sure your device is connected and recognized by Odin.

8. Click start.

9. One the phone reboots run the ADB command, adb reboot bootloader

I used these instructions to install adb and fastboot in windows. I also did the option in the article to make it so you can type commands from any directory to get commands to your phone: http://lifehacker.com/the-easiest-way-to-install-androids-adb-and-fastboot-to-1586992378 Once you get to this step you will just type ADB reboot bootloader in the command prompt.

10. Open modded Odin and flash the EngBoot This is where you add the EngBoot file you downloaded to the BL section in Odin (the princecomsy modded odin). If for some reason you open odin and try to add the zip file to the BL section and it isn't showing up as a valid file, then unzip the file and try looking in the unzipped file.

11. Click start

12. Once the phone reboots type the command adb reboot bootloader

13. Put the HOME_CSC of the G950W firmware into the CSC part of Odin (unmodded) - For me it wouldn't work on the unmodded Odin so I used the princecomsy odin but definitely try the unmodded first.

14. Click start

15. Open IME setting on Factory Binary - When the previous step finishes it will boot your phone into the factory binary and you will literally see an icon saying "IME setting", you click this and then do the next step.

16. Type in *#243203855# type exactly as shown and it will bring up a bunch of options where you will do the next step

17. Select XAC

18. Click install

19. Wait for phone to reboot

20. Once it does open terminal and type in adb shell - this is the same as previous commands, you type ADB shell exactly as shown

21. Then type in echo "XXX" > /efs/imei/mps_code.dat type this exactly as shown, fyi there's a space before and after the >. Replace the XXX with the carrier code you plan to convert to (see original post for a list of carrier codes)

22. Type in exit into adb shell - just type exit in the command prompt to get out of the shell

23. Type in adb reboot bootloader

24. Flash the G950U firmware of your choosing without Userdata. Also make sure to flash the non-home CSC - download the correct firmware for your phone (950 or 955 for s8 and s8+) from sammobile or updato. you will unzip these to reveal the files. There will be an BL, AP, CP, and CSC files (and possible a Home_CSC and USERDATA file). Open odin (i tried the princecomsy odin but got a mismatch error so I ended up using the unmodded odin) and add the AP file to the AP section, BL to the BL and so on (do BL, AP, CP, CSC (NON HOME VERSION). Make sure you phone is in download mode (power+bixby+volume down, will saying downloading or something). Press start and it will do a ton of stuff. Once it all installed my phone rebooted and tried installing but got stuck at 32% and I was able to boot into the phone but things were missing and not complete. So I did a complete restore by just going to the erase and restore option in the actual phone settings (or whatever it's called) and everything works perfectly now.

25. Enjoy your new carrier!