[Magisk] mrbeem:
Ok great. Now what you must do is:

1. Delete folder _COMMON

2. Create new folder called SUPERSET

3. Copy everything from folder OPEN-EU to SUPERSET. Make sure you have permissions 755 set for SUPERSET folder.

4. In SUPERSET/cust.prop, at the end of second line change OPEN-EU to SUPERSET

5. In OPEN-EU/cust.prop, at the and of second line change OPEN-EU to GLOBAL-COM

6. In /OP delete file client_id.xml

7. In cust_path_mapping.cfg make sure you have a following line: 999999,99=/OP/SUPERSET. If not, add that line

8. In cust_group_mapping.cfg there should only be 1 following line: ro.lge.cupssgroup=OPEN-EU, so edit your file the way it only has that line.

9. In op_list.cfg make sure you have a line 999999,99=/OP/SUPERSET. If now, add that line

10. In /system/vendor/overlay create 2 folders with 755 perms.

- folder 1: com.android.framework-res

- folder 2: com.lge.framework-res

11. Go back to /OP/SUPERSET, in there open folder /overlay/framework/ and there should be framework-res.apk there. Copy this apk into both folders you just created in /system/vendor/overlay and set perms to 644.

12. Edit open your build.prop file in /system and at the bottom add the lines i posted earlier on. Most important line is persist.lg.data.iwlan.enable=true

Also make sure you add persist.lg.data.iwlan=1 and persist.lg.data.iwlan.ipsec.ap=1 . But you must paste everything from my post above, not just those 3 lines. Best just copy/paste all build.prop lines from my post above. Now save your build.prop file and reboot. It might happen that afret making changes in cust.prop in /OP/SUPERSET or

/OP/OPEN-EU you will be bombed with alot of apps force closing. Don't worry about that, just reboot your phone and everything will be ok. Carry on with rest of the changes described.

If after all that your WiFi calling does not work you have to clean install an unrooted branded WiFi Calling enabled rom from your carrier in .kdz using LGUP, flash TWRP again, decrypt, root. Check if WiFi calling is working on your carrier's rom (not any rom but one that has WiFi Calling enabled) if yes, then flash Fulmics ROM straight over your carrier's rom. This way you will have all the files from your carrier's WiFi Calling enabled ROM in Fulmics /OP directory. Your carrier's folder will have XXX_XX name (for example VDF_IT for vodafone italy). Then, on your carrier's folder you must repeat all the above steps you did with your OPEN-EU folder.

Above anything... You will not be able to activate WiFi Calling on your device if you device is not on the list of your carrier's devices with support for WiFi Calling or if your provider uses an external app for WiFi Calling.

To check if your device is supported go to your apns list in settings and make sure you have apns called IMS and XCAP listed there. If not, go to your carrier's website and read about how to activate WiFi calling for your phone number. My carrier requires sending a text msg START to 282. I did it and they sent me service message with extra apns for WiFi Calling. If you don't have IMS and Xcap in your apns WiFi Calling will not work for you and adding those apns manually will not help either unless your provider requires manual add of those apns for supported devices.