Should work on all Snapdragon USA/Canada models (ATT , verizon, sprint, tmobile tc) Tested on S8+ and S8, should work on Note 8 if you have right files. S9 switched to a different CSC format, so it's not possible to use this method for S9 models.
Keep your Jio/Any other VoLTE enabled indian carrier SIM in the phone all along.
Check your Bootloader version first (Download matching files only)
1.Back up your data using Samsung smart switch or any other means (save whatsapp chats to google in settings)
2.Flash matching stock firmware (On unzipping stock FW, you'll get AP, CP,BL and CSC files. Use Odin to flash them) (Don't flash User data file if it's there in extracted files)
Recommended Odin https://forum.xda-developers.com/and...-13-1-t3762572
Please find latest stock roms on Updato website
CRE2 for BL version 1, 2,3
or CRE9 for BL 4
CRE2 for BL 1,2,3 or CRE9 for BL4
Note 8 models
BL 1,2,3 or CRE1 for BL4
3. Download sec_omc.zip specific to your model
INS OMC Dec 2018 version for s8+ or For Note 8 or For S8
4. Download and unzip combination rom (You'll get a file ending in tar.md5) (Matching file only)
For s8+ models or Mirror, Another mirror with BL5 files
Another for BL5
For s8 Models or
another mirror for S8
Note 8 combination files or Mirror or BL 4 version BL5 version
If you want updated combination files of the same models, search on xda or shell.boxwares.com or firmware.gem-flash.com yourself before asking others.
5. Open Odin (princecomsy version) and click on AP, choose the file you extracted in step 4
6. Put your phone in download mode (hold the Power button, Volume Down button, and the Bixby button until Download mode screen is seen. Press Vol up to confirm).
7.Connect your phone to PC. You should see "Added" in log of Odin and see a com port appearing on top left.
8) Click on start tab. If everything goes well, you'll see "PASS" on top left. Let it boot to Factory binary once.
9) Boot your phone to recovery mode (hold the Power button, Volume up button, and the Bixby button until samsung screen is seen).
10) Install "minimal ADB fastboot" program on PC, Copy the sec_omc.zip to your minimal ADB folder on computer (under program files on C drive).
Double click cmd-here.exe in that folder.
11) Connect your phone to your computer with your USB cable and in phone select Apply update via ADB in recovery screen (Navigate with vol bottons and select with Power btn).
12) On ADB window on PC type "adb devices" without quotes. Next line should show a device attached
If seen, type "adb sideload sec_omc.zip" without qoutes. It'll start transferring the file.. check mobile screen it'll install itself. (you might see some errors)
13) Once your phone reboots, you will see an "IME" button on the bottom). Tap on it and type *#243203855#
14) On resulting window, if you see INS in the list, click over it and click install and select full customisation.
15 Your phone will reboot to the 'factory binary homescreen', go to ADB on your computer and type in "adb shell".
16) Type in echo "INS" > /efs/imei/mps_code.dat (Please make note of the space between " and > and /)
You won't get any confirmation.
17) Now flash the full Stock firmware matching your bootloader via ODIN (BL, AP, CP, CSC files (not home csc)
18) After the flashing, phone will reboot. Don't setup any accounts yet. Boot to recovery and select "apply update via ADB" (Like step 11)
19) Sideload the CSC zip (similar to step 12) and let it reboot.
20) On reboot, you should see INS/INS/xxx under software info (xxx is your factory csc version) and VoLTE icon should appear.
1. Phone app force closing
Reflash AP BL CP only excluding CSC
Install OMC zip via adb
2. Messaging app FC
Install S9 sms app or google messaging
2. Sprint OMADM app needs to be removed to avoid annoying notification or change notifications to low priority
To remove via ADB, turn on usb debugging
type in adb shell
you should see a dollar sign.
next type in pm uninstall -k --user 0 com.sec.omadmspr
it should say success.
If you want to extract OMC zip for a different model device, watch this video.
The file needed to extract is attached to this post (omc extract)
Thanks to @jrkruse for the idea of flashing CSC zip from exynos to snapdragon
@Mike15678 for carrier switch thread
@chetan180 for trying carrier switch to INS
@anarasgarli for combination files links