[LG G5 Guides, News, & Discussion] akki7636:
You are Responsible for what you do to your phone. Don't Blame me for ANYthing. BACKUP before making any changes

NOTE-

-This method consists of Editing Build.prop & Volte configuration file in cust folder.

- This method may not work for all but it will give you some idea about how things are going on.

- Im not a Developer and English is not my native language.

Complete method and explanation-

Step 1- (For fulmics rom you can skip this step as volte in build.prop is already enabled)

Editing build.prop file

GO to build.prop file in System folder via any root explorer and paste this command at last.

ro.lge.supportvolte=1

After pasting this command , leave a blank line at last and save. Now reboot your phone , it will enable Volte option in call or network setting. Some people achieve volte services only by doing this step but if volte button in setting dont do anything , proceed to step 2.

Step 2(General)-

Editing a file in cust folder.

Go to Cust > open_com >_config > config_open_eu > vo_config.xml

In this file replace MCC and MNC values according to your region and network. Reboot.

Step 2 (For fulmics rom , guided by [MENTION=5132229]xpirt[/MENTION] )-

A-Add following 2 lines at the end of build.prop with a blank line at last

ro.lge.capp_cupss.rootdir=/cust
ro.build.sbp=1

B- Flash the zip in attachment.( It will add cust folder contents with correct permissions. If this method fails or you face any issues you can delete all the files and folders from cust folder)

C- Follow step 2 (General)

Step 2 with Explanation and Guidance

Maximum time we don't have volte services because we are using a phone of different region or with a carrier other than default.

Cust folder consists of settings and configurations related to the region and carrier. Whenever our phone boots up it detects the carrier or region in which we are using our phone and load the settings according to the network or region. For detection and loading desired configuration phone use 2 codes MCC (mobile country code) and MNC (mobile network code ). You can find mcc and mnc from apn setting or just google including your country and carrier.

For example i am having european h850. so the configurations for all the european countries and their carriers are stored in cust folder. Now what if i boot up the phone in the region other than europe or started using a carrier not included in cust folder or delete all files in cust folder. In this case phone loads the " Open Com " configuration which are not specific to any carrier or region.

So for this method our phone must have all files in cust folder ( in fulmics rom cust folder is empty ) and our phone must be booted with 'opencom' configurations . If you are using any customised stock rom (for h850) or if in software version (under 'about phone' ) you see 'euroxx' it may be means your phone is booted up with '' open com '' configurations.

Now via any root explorer go to -> Cust > open_com >_config > config_open_eu > vo_config.xml

In this file replace MCC and MNC values according to your region. and reboot. That's it :)

All this worked for me on h850. I dont know about other models.. You can use theory in your own way.

Thanks to [MENTION=5132229]xpirt[/MENTION]

Hit thanks if helped