[Realme GT Neo 2] darkhunter9:
This post records how I combine many tutorials online and finally enable VOLTE and VoWifi on my Realme GT Neo 2 while the toggles are not available at the beginning.

TLDR: Most Realme devices support VOLTE and VoWifi, but the toggles may not be available in countries where Realme is not sold officially. However, they could be enabled by editing the build.prop file. Root and Magisk are necessary. Using Magisk, services like Google Pay can still work properly (price is potentially less security).

As we all know, most Realme devices support VOLTE and VoWifi, and usually you can find and activate them easily in Settings->Mobile network->SIM-> SIM info & settings. There are many tutorials on the website. However, in countries where Realme is not sold officially, you may not find these 2 toggles. I'm not sure about the exact reason but some are saying that local operators have strict whitelist policy (like ATT and TMobile), and of course a device sold only overseas won't be on it.

My situation​

I bought a Chinese version Realme GT Neo 2 and the bands are compatible with Tmobile 4G (link). After getting the phone, I refer to this post to flash the global version firmware. My operator is Mint, a mvno of Tmobile and I cannot find VOLTE or VoWifi toggles. After reading this post and using an app called ForceLTE, I'm able to use 4G data. But whenever I make a phone call, the signal jumps back to 3G and data becomes H+(HSDPA). Recently Mint sent me a message, saying that they are retiring 3G soon and my device is not compatible. After a certain date, my phone will not be able to make/receive phone calls if still relying on 3G.

IMEM check fails on Tmobile, Mint, and ATT websites.

On Xiaomi devices there's a code used to activate VOLTE directly, on Oneplus devices you can use log app, but no similar way can be found for Realme devices.

This method I find could be applied to other Realme devices in other countries when the toggles are not available in SIM info & settings.

Disclaimer​

Please try the posts I mentioned first.

This method requires root. Take your own risk for any of your behaviors.

I'm not responsible for any of your losses (including, but not limited to device, finance, data, personal info)

Device info​

Realme GT Neo 2 chinese version

Global version firmware (RMX3370_11_C.02) via TWRP

Bootloader locked after flashing the firmware

Steps​

1. Unlock the bootloader (refer to this post). Attention: unlock will get all data wiped!

2. Install TWRP (refer to this post) and Magisk (refer to this post).

Attention: even after you flash TWRP.img to the recovery partition, if you keep using stock firmware (no matter what region/version), recovery will go back to stock one after the first time you boot to the system. You'll have to install Magisk (or use 3rd party firmware) to keep TWRP

3. Install MagiskHide props config (refer to this post) to allow us to edit the build.prop file. It is in system partition (ext4, read-only), and can no longer be edited directly (even if you try to remount it in TWRP or ZArchiver with -rw).

4. Install a terminal emulator from google playstore. Android is a linux system, imagine this app as a window you can open on your PC with linux to input commands.

5. In the emulator,

5.1 type "su" and enter

5.2 type "props" and enter

View attachment 5640895

5.3 type "5" and enter (Add/edit custom props)

5.4 type "n" and enter (New custom prop)

5.5 type "persist.dbg.ims_volte_enable" and enter (the prop we want to add)

5.6 type "1" and enter (enter your desired option)

5.7 type "y" and enter (Enter y(es), n(o), e(xit) or an option from above)

5.8 type "n" and enter (do you want to reboot now)

5.9 repeat step 5.3-5.8 for the following props:

persist.dbg.ims_volte_enable, type "1" in step 5.6

persist.dbg.volte_avail_ovr, type "1" in step 5.6

persist.dbg.vt_avail_ovr, type "1" in step 5.6

persist.dbg.wfc_avail_ovr, type "1" in step 5.6

persist.radio.rat_on, type "combine" in step 5.6

persist.radio.data_ltd_sys_ind, type "1" in step 5.6

persist.radio.data_con_rprt, type "1" in step 5.6

persist.radio.calls.on.ims, type "1" in step 5.6

In step 5.8 after you finish entering the last prop, type "y" and enter (reboot now)

6. After reboot, check whether 2 toggles are there in Settings->Mobile network->SIM-> SIM info & settings

View attachment 5640909

7. If you still want to properly use apps like Google Pay after root, refer to this post

Test if VOLTE and 4G network work​

1. In settings->Notifications & status bar->Status icons, make sure you turn on VoLTE, VoWiFi and Mobile network

2. If you are connected to a wifi and VoWifi works, you should see a small wifi sign above telephone sign in status bar, like this

View attachment 5642983

In addition, for Tmobile, in Settings->Mobile network->SIM1, the Carrier is shown as T-Mobile Wi-Fi Calling (for mvno like mint, don't forget to turn it on on mint website->personal settings first).

3. Disconnect the wifi, you should see "4G" above the network sign, as well as VoLTE sign in the status bar. Turn on data, make a phone call (such as voicemail), minimize the window, check if "4G" sign is still there. Finally, with the call going on, try openning a website like Google. If "4G" sign is there during the whole process, congratulations!

View attachment 5642987

Let me know if this works for you, or if you have any questions/suggestions. Thanks!