[GUIDE] [NO ROOT REQUIRED] [EPIC UPDATE] How to add VoLTE support for other carriers to the G8 (and other Qualcomm powered LG devices too!)

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suifong

Member
Feb 6, 2013
18
0
I extract Stock rom
Open modem.img with 7z
But there is no mbn file with my region only NA or KR
 
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suifong

Member
Feb 6, 2013
18
0
I've already mentioned the names of the mbn files that i can see on my G8S, unfortunately i can't see them when i extract files from modem_a using 7z.
I'm hoping you can share the LG default mbn file so that i can try it on the G8.

Regarding how i got VoLTE to work on my G8 phones, it was a long story of trial and error, but what finally works is replacing these files in /product/OP/config with files from the Indian G8S - apns.xml, carrier_code.xml, telephony.xml and vo_config.xml. In the last file, don't change the name of the operator or country,
Hello where can I find those files I open my region rom

I open my region rom system_a.img system\product\ folder is empty
 
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I crossflashed my ATT Locked G8 to Can version and voLTE doesn't work. I followed this guide but I already had one ATT file loaded onto the phone. I loaded the one from the tutorial as well and now I have two ATT files but they seem to be different, one says active and one doesn't. Is this what I should have done or did I miss something? voLTE still doesn't work, calls fail immediately.
 

SumoCat

Member
Oct 12, 2019
5
0
Just an FYI in case this might help someone:

On my G8 the mobile network connection for LTE was listed as GSM/CDMA/LTE (auto). I could barely connect to LTE with this enabled (always connected to EDGE).

In the field test menu switch the mobile network to LTE only. Back in your network setting it will say "preferred network mode: 11"

Now my phone always connects via LTE.
 

BereiBlue

Member
Dec 23, 2015
42
1
This guide will not work if you are running Android 12 :(

I'm gonna keep the intro simple, been a longtime user here on XDA, and recently I found that my T-Mobile LG G8 only supported VoLTE and VoWifi on, you guessed it, T-Mobile! So I did some research, experimented with my G8 for a bit, and I now have a method that works and does not need root at all. Basically, what we are doing here is just loading carrier profiles into the phone's modem so that the phone is able to complete IMS registration and correctly provision VoLTE when you insert a SIM card from another carrier.

If you are trying this on a LG V60, please turn off USB debugging before attempting this as multiple V60 owners have had trouble properly installing the modem driver and only resolved the driver issue by turning it off. Also, please try the 90E5 driver if the 9091 driver does not work for you.

This method does not work on the Sprint G8, any other Sprint LG devices, the Korean G8 and any other Korean LG devices since there is no Field Test option in the HiddenMenu in those devices.


Follow this post here, and make sure you read the original post in that thread as well. Also should work with other BL unlocked G8 models. Crossflash your G8 to Open US or Open CA firmware using this method! No unlocked bootloader or root needed!

DO THIS FIRST!!!!!: STEPS TO OBTAIN CARRIER MBN FILES FOR YOUR DEVICE (MBN files for the G8/G8x/G8s provided in Step 11 of the main guide)

1. Download a KDZ for your device. Sites like lgrom.com or lg-firmwares.com have KDZ's available to download. If you have an AT&T LG device just download a KDZ for another variant of your phone. Ex: If you have the AT&T LG Velvet, just download the Canadian Velvet's KDZ. Same for the AT&T G8, G8x etc.

2. Download and install
7zip, and the linked/attached KDZ extractor tool.

3. Extract the KDZ tool zip file, then place your downloaded KDZ into the same folder as the KDZ tools.

4. In the KDZ tools folder, find "OneKeyExtraction.bat" and double click on it.

5. When the CMD windows launches, press Y to start extracting the partitions from the KDZ.

6. Once it is finished, you should see a new folder in the KDZ tools folder that has the same name as the KDZ that you downloaded. Open up that folder.

7. As you can see the tool extracted all of the partitions that are contained in the KDZ file. We will need to open up either the modem_a or modem_b partitions to grab the needed MBN files. Scroll down to find those partitions. Doesn't matter which one you choose.

8. Right click on whichever one you chose, hover over "7zip", then click "Open archive".

9. 7zip will open up. The folders where the MBN's will be vary by device. Generally you should first look for a folder named "modem_pr", then once in it find the "mcfg_sw" folder. Here are some examples to help you find where the MBN files in your device's modem partition are. The files will be seperated into folders by region and carrier.



10. Once you find the files, extract them to whichever folder you want to.



Now here are the steps to load the MBN's:

1. Download the latest QPST Tools from here. Only runs on Windows. No Linux, sorry.

2. Extract the zip file you downloaded and open QPST.2.7.496.1.exe to install the QPST tools.


3. Once that is done, go to the Driver folder and open Qualcomm USB Driver V1.0.exe to install the drivers needed for the tool to communicate with your phone.

4. After that is done, there should be a QPST folder in your start menu. We'll come back to that later.

5. On your phone, go to the dialer and enter this code:
Code:
*#546368#*xxx# OR #*462633*#xxx# *xxx is the three numbers in your device's model code.

6. The HiddenMenu should pop up, choose Field Test, then LTE Data Test, and change the Tethering Mode from Android to QMICM. I recommend leaving your phone in this menu so that it is easier to switch back to the normal Android USB connection mode when you are done.


7. Connect your phone to your computer, it should be detected as "Qualcomm HS-USB Modem 9091". In Device Manager it should show up under the Modems section.

8. Go to the QPST start menu folder and open the "PDC" application.

9. Go to the Device dropdown, there should be an item named "Qualcomm Wireless HS-USB Ethernet Adapter 9091". This is your phone, select it.
10. This is what you should see. Notice how only the original carrier's (T-Mobile) modem profile is loaded into the phone's modem. Pretty lazy if you ask me.
11. Now you will need some modem profiles to load into your phone! As a little starter pack, here are a few carrier modem profiles for US, Canadian and Korean carriers. Download them here (these are only for the G8/G8x/G8s! Will not work with other devices!!!!!!). I have extracted these from my phone's modem_a partition using QFIL Partition Manager with the LG SD855 firehose, and these are present in the modem_b partition as well. LG left all of these profiles inside the phone but only actually loads one of them into the modem on carrier models....

These profiles may also work on the G8x, V50, and G8s since those phones have the same SOC as the G8, and by extension the same modem chip.

12. Once you are ready, press the Load button and navigate to whichever carrier profile you want to add, I will load AT&T as an example. After going inside the folder for the carrier you want to load, there should be a file named "mcfg_sw.mbn". This is the profile. Don't bother adding any profile that has "row" in it's name, those usually don't give you support for VoLTE.
13. When you are ready, click Open and your carrier profile will be loaded into your phone! You can go and add as many carriers as you want, I loaded all US and Korean, and some Canadian carrier profiles into my G8.

Do not load the same profile multiple times, this may cause issues with VoLTE and cell connectivity.

14. When you are done, go back to the LTE Data Test menu and set the tethering mode back to Android. Your phone now has VoLTE support for the carriers that you loaded into it!

If you have another Qualcomm LG device, you can also follow this guide, you just need to enter the HiddenMenu dialer code specific to your device, and have carrier config files that are either specifically for your device, or from another phone that has the same chipset as your device* (*may or may not work).

Here's AT&T VoLTE working with a Tracfone AT&T sim card on my previously incompatible T-Mobile G8:

Hope this guide has helped you guys!
Can you please help me figure out why volte is working on one NA Open KDZ but not on another?

On "G850QM30b_00_NAO_US_OP_0902.kdz" volte works fine and I am able to open IMS settings from the Field Test menu.

On "G850QM30c_00_NAO_US_OP_0224.kdz" I am able to open IMS settings from the Field Test menu after flashing BUT as soon as I put in my sim card, I am no longer able to open the IMS settings, even if I remove my sim card the IMS settings will not work. When I press on the IMS setting a toast notification says "Ims(MmTel): Not Support".

I have made sure the correct MBN is loaded and made active ( also made sure it displays correctly in mcfg status ) but that does not make a difference. I have also tried injecting "Modem_A" and "Modem_B" from KDZ 30b into the phone and that also made no difference.


Edit: BPT KDZs are "fake" US Open roms. USA and CCA (have the same hash) are "real" US Open roms. That is why VoLTE work on 30b but not 30c.
 
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Wish39

Senior Member
Jan 13, 2015
206
59
I crossflashed my ATT Locked G8 to Can version and voLTE doesn't work. I followed this guide but I already had one ATT file loaded onto the phone. I loaded the one from the tutorial as well and now I have two ATT files but they seem to be different, one says active and one doesn't. Is this what I should have done or did I miss something? voLTE still doesn't work, calls fail immediately.
If you want VoLTE on all US carriers flash G820QM US unlocked firmware, don't flash Canadian G820UM firmware because VoLTE wont work on that firmware. I also said in the guide to NOT have two of the same profiles loaded into the phone, delete the inactive one.
 

Wish39

Senior Member
Jan 13, 2015
206
59
Can you please help me figure out why volte is working on one NA Open KDZ but not on another?

On "G850QM30b_00_NAO_US_OP_0902.kdz" volte works fine and I am able to open IMS settings from the Field Test menu.

On "G850QM30c_00_NAO_US_OP_0224.kdz" I am able to open IMS settings from the Field Test menu after flashing BUT as soon as I put in my sim card, I am no longer able to open the IMS settings, even if I remove my sim card the IMS settings will not work. When I press on the IMS setting a toast notification says "Ims(MmTel): Not Support".

I have made sure the correct MBN is loaded and made active ( also made sure it displays correctly in mcfg status ) but that does not make a difference. I have also tried injecting "Modem_A" and "Modem_B" from KDZ 30b into the phone and that also made no difference.
Which cell carrier do you have? Also no need to mess with the IMS settings, if you want to try forcibly enabling VoLTE, please try this:
1. Create a new folder in your internal storage named "enable_ue"
2. Dial #546368#*820
3. Go into field test==>universal enabler
4. Click "Create New Config"
5. Then enable all 4 boxes and see if VoLTE will work
 

BereiBlue

Member
Dec 23, 2015
42
1
Which cell carrier do you have? Also no need to mess with the IMS settings, if you want to try forcibly enabling VoLTE, please try this:
1. Create a new folder in your internal storage named "enable_ue"
2. Dial #546368#*820
3. Go into field test==>universal enabler
4. Click "Create New Config"
5. Then enable all 4 boxes and see if VoLTE will work
I have T-Mobile. From my experience with LG phones VoLTE will never work if IMS settings give an error and doesn't open. I had tried universal enabler too, still nothing.

Now there is a new problem for my phone.
I'm now on A12 US Open and the IMS settings do open but mcfg status is incorrect, so calls don't work. I can't get calls to work because mcfg/mbn is stuck on ROW_ATT and I have T-Mobile.

Do you know if it is possible to take the Modem_a partition/img and delete all but one MBN and inject the partition back into the phone? That way the phone is forced to load just that one MBN.

Also, I wouldn't be surprised if LG screwed up (or something) on their A12 roms for auto MBN selection; given the fact that QMICM is also screwed up and no longer working on A12.

I'm curious what the MCFG status is on a "real" (non-crossflashed) QM phone running A12 and the sim card/carrier being non-ATT.
 

Wish39

Senior Member
Jan 13, 2015
206
59
I have T-Mobile. From my experience with LG phones VoLTE will never work if IMS settings give an error and doesn't open. I had tried universal enabler too, still nothing.

Now there is a new problem for my phone.
I'm now on A12 US Open and the IMS settings do open but mcfg status is incorrect, so calls don't work. I can't get calls to work because mcfg/mbn is stuck on ROW_ATT and I have T-Mobile.

Do you know if it is possible to take the Modem_a partition/img and delete all but one MBN and inject the partition back into the phone? That way the phone is forced to load just that one MBN.

Also, I wouldn't be surprised if LG screwed up (or something) on their A12 roms for auto MBN selection; given the fact that QMICM is also screwed up and no longer working on A12.

I'm curious what the MCFG status is on a "real" (non-crossflashed) QM phone running A12 and the sim card/carrier being non-ATT.
Downgrade to 30b A11, follow the guide to open up PDC and remove the ROW_ATT profile. While you're in there just add the profiles for all of the US carriers, and then set the TMO profile to active. See if VoLTE works on A11 first, then if it does try seeing if it works on A12. Sounds like something is broken in 30c.
 

BereiBlue

Member
Dec 23, 2015
42
1
See if VoLTE works on A11 first, then if it does try seeing if it works on A12. Sounds like something is broken in 30c.
Yes, VoLTE works on A11 30b. A12 40b doesn't work because no one can get access with pdc to change the active mbn.

That is why I want to learn how to take the partition and modify it to have just one mbn. It should be possible because I was able to successfully boot 30c rom with a 30b modem_a.

30c isn't exactly broken, it is just not truly open. I did not realize this until I looked at the g820qm 30c KDZs. The KDZs CCA and USA have the same hash for 30c but the one for BPT 30c is different (also has different build date). Whatever that difference is idk, but it does stop IMS/VoLTE from working on my phone.
 

Wish39

Senior Member
Jan 13, 2015
206
59
Yes, VoLTE works on A11 30b. A12 40b doesn't work because no one can get access with pdc to change the active mbn.

That is why I want to learn how to take the partition and modify it to have just one mbn. It should be possible because I was able to successfully boot 30c rom with a 30b modem_a.

30c isn't exactly broken, it is just not truly open. I did not realize this until I looked at the g820qm 30c KDZs. The KDZs CCA and USA have the same hash for 30c but the one for BPT 30c is different (also has different build date). Whatever that difference is idk, but it does stop IMS/VoLTE from working on my phone.
USA is the region code you want if you want to flash the truly unlocked firmware. BPT (Brightpoint) firmware probably doesnt have support for other carrier's VoLTE.

The MBN's dont work like that, you need to actually load the MBN's into the phone using PDC. I crossflashed a Sprint G8 to 30b as well and the MBN's didn't magically get loaded into the phone. It still only had Sprint MBN's still loaded in.

Another fun fact is that every G8 model and firmware actually has all of the MBN's for Korean, Canadian and US carriers included inside of the modem partitions. But depending on carrier and models only some are loaded in by default.
Ex: Only ROW_ATT, FirstNet and ATT will be loaded in on an AT&T G8. Only ROW_TMO and TMO were loaded in on my T-Mobile G8.

The extracted G8 MBN's that are in the first post were extracted from my T-Mobile G8 on T-Mobile firmware.

For the active MBN, the phone will set the active profile by itself depending on what carrier sim is in it. Just make sure that there are no ROW_xxx profiles loaded in as the phone might keep defaulting to those profiles instead.
 

BereiBlue

Member
Dec 23, 2015
42
1
The MBN's dont work like that, you need to actually load the MBN's into the phone using PDC. I crossflashed a Sprint G8 to 30b as well and the MBN's didn't magically get loaded into the phone. It still only had Sprint MBN's still loaded in.
I agree with you for A11, for me it was also the same as you on my sprint phone using A11. On A11 I had only SPR loaded, and it was the only carrier in pdc.

On A11 I used PDC to only load ATT, TMO, VZW and I made TMO active. I never loaded any ROW mbn or any OPEN mbn. I also deleted SPR.

On A12 it has ROW_ATT active but I did not load ROW_ATT because you can't use PDC on A12. Therefore, the phone is loading and activating ROW_ATT by itself. I swear.

If the phone is able to load ROW_ATT on its own, then it should be able to load TMO if I can make it the only one available in the rom/partition.
 

amit2046

Member
Oct 17, 2016
35
4
New Update!!

VoLTE and Vowifi finally working on Airtel.

Right after my last reply, it occurred to me that I should try my wife's SIM in my phone. And when I did, VoLTE and Vowifi were working on my phone.

So I rushed back to the Airtel store and after explaining everything, and even getting them to put of their SIM in my phone they raised a ticked to fix the problem.

And now in the evening I got a call from airtel to check - thankfully it's working. Ims also showing as registered.

For some reason it still doesn't seem to detect my phone number - but as long as volte and vowifi work I couldn't be bothered.

I'll check Jio and Vodafone when I can get my hands on a sim.

Thank you very much for your replies, files and advice. Cheers.
Hi Sykander,

Can you help me here?

I am using LG V60, T-Mobile version, Android 12 and on Airtel
 

PHANX0M

Senior Member
Jun 6, 2015
86
6
Sony Xperia Z5 Premium
LG G8
I crossflashed my ATT Locked G8 to Can version and voLTE doesn't work. I followed this guide but I already had one ATT file loaded onto the phone. I loaded the one from the tutorial as well and now I have two ATT files but they seem to be different, one says active and one doesn't. Is this what I should have done or did I miss something? voLTE still doesn't work, calls fail immediately.
Crossflash the Open_USA one from QM onto your UM
and when you're done, flash back the original FTM file ☺
Almost had same problem bro. But when I tried Android 9 with Open_US calls DIDNT work. But the ones after do.
ONLY DO THIS AFTER BACKING UP ALL THE PARTITIONS (it's said the he who doesn't back up all his partitions's destined to die alone with no wife and kids)


 
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rrhhuutt

Member
Aug 25, 2022
5
0
I own an AT&T "network locked" LG G8 and was able to use it with H2O Wireless (AT&T reseller) since I purchased it brand new in the sealed box back in late November 2021. Everything was absolutely fine until 3G was turned off back in March, where I couldn't place nor receive calls. I called H2O support and after explaining instruct me to recreate the APN, and after I did so I could place and receive calls for just a few minutes. So I called H2O again and decided to send me a new SIM card. A few days later I received it, activate it and still the same thing, so I put my G8 to the side. Fast forward to this past weekend, I called H2O again and this time they told me I had to create the following two APNs:

Name: H2O Internet
APN: prodata
MMSC: http://mmsc.mobile.att.net
MMS proxy: proxy.mobile.att.net
MMS port: 80
APN type: default,mms,supl,hipri
APN protocol: IPv4

Name: H2O Call
APN: nxtgenphone
MMSC: http://mmsc.mobile.att.net
MMS proxy: proxy.mobile.att.net
MMS port: 80
APN type: default,mms,supl,hipri
APN protocol: IPv4

The thing is that the only way I could place and receive calls is by selecting H2O Call APN, but don't have any data, and if I choose H2O Internet I get data but no calls.

Yesterday a friend let me borrow his AT&T SIM for a couple of minutes to do some testing and for the first time ever I could see a new icon on my screen that showed VoLTE. I was able to place, receive calls and have all LTE data that I want using AT&T's default APN. Right now I'm out of ammo wondering if there's a workaround to fix this VoLTE issue...

Any idea will be more than welcomed ! ! !
Have you solved the issue? I have the same issue. My unlocked LG G8 (ATT) worked smoothly with H2O sim card until it is upgraded to Android 11. It cannot make/receive calls, but data/text are good. When I inserted an ATT sim card, everything worked well. I guess ATT probably has done something to block competitors.
 

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    This guide will not work if you are running Android 12 :(

    I'm gonna keep the intro simple, been a longtime user here on XDA, and recently I found that my T-Mobile LG G8 only supported VoLTE and VoWifi on, you guessed it, T-Mobile! So I did some research, experimented with my G8 for a bit, and I now have a method that works and does not need root at all. Basically, what we are doing here is just loading carrier profiles into the phone's modem so that the phone is able to complete IMS registration and correctly provision VoLTE when you insert a SIM card from another carrier.

    If you are trying this on a LG V60, please turn off USB debugging before attempting this as multiple V60 owners have had trouble properly installing the modem driver and only resolved the driver issue by turning it off. Also, please try the 90E5 driver if the 9091 driver does not work for you.

    This method does not work on the Sprint G8, any other Sprint LG devices, the Korean G8 and any other Korean LG devices since there is no Field Test option in the HiddenMenu in those devices.


    Follow this post here, and make sure you read the original post in that thread as well. Also should work with other BL unlocked G8 models. Crossflash your G8 to Open US or Open CA firmware using this method! No unlocked bootloader or root needed!

    DO THIS FIRST!!!!!: STEPS TO OBTAIN CARRIER MBN FILES FOR YOUR DEVICE (MBN files for the G8/G8x/G8s provided in Step 11 of the main guide)

    1. Download a KDZ for your device. Sites like lgrom.com or lg-firmwares.com have KDZ's available to download. If you have an AT&T LG device just download a KDZ for another variant of your phone. Ex: If you have the AT&T LG Velvet, just download the Canadian Velvet's KDZ. Same for the AT&T G8, G8x etc.

    2. Download and install
    7zip, and the linked/attached KDZ extractor tool.

    3. Extract the KDZ tool zip file, then place your downloaded KDZ into the same folder as the KDZ tools.
    1646120728815.png

    4. In the KDZ tools folder, find "OneKeyExtraction.bat" and double click on it.

    5. When the CMD windows launches, press Y to start extracting the partitions from the KDZ.

    6. Once it is finished, you should see a new folder in the KDZ tools folder that has the same name as the KDZ that you downloaded. Open up that folder.
    1646121613132.png

    7. As you can see the tool extracted all of the partitions that are contained in the KDZ file. We will need to open up either the modem_a or modem_b partitions to grab the needed MBN files. Scroll down to find those partitions. Doesn't matter which one you choose.

    8. Right click on whichever one you chose, hover over "7zip", then click "Open archive".
    1646122181314.png

    9. 7zip will open up. The folders where the MBN's will be vary by device. Generally you should first look for a folder named "modem_pr", then once in it find the "mcfg_sw" folder. Here are some examples to help you find where the MBN files in your device's modem partition are. The files will be seperated into folders by region and carrier.
    1646122816648.png

    1646122875662.png

    1646122958551.png

    10. Once you find the files, extract them to whichever folder you want to.



    Now here are the steps to load the MBN's:

    1. Download the latest QPST Tools from here. Only runs on Windows. No Linux, sorry.

    2. Extract the zip file you downloaded and open QPST.2.7.496.1.exe to install the QPST tools.

    1633495073816.png

    3. Once that is done, go to the Driver folder and open Qualcomm USB Driver V1.0.exe to install the drivers needed for the tool to communicate with your phone.

    4. After that is done, there should be a QPST folder in your start menu. We'll come back to that later.

    5. On your phone, go to the dialer and enter this code:
    Code:
    *#546368#*xxx# OR #*462633*#xxx# *xxx is the three numbers in your device's model code.

    6. The HiddenMenu should pop up, choose Field Test, then LTE Data Test, and change the Tethering Mode from Android to QMICM. I recommend leaving your phone in this menu so that it is easier to switch back to the normal Android USB connection mode when you are done.

    1633495857477.png
    1633495872107.png
    1633495890722.png

    7. Connect your phone to your computer, it should be detected as "Qualcomm HS-USB Modem 9091". In Device Manager it should show up under the Modems section.

    8. Go to the QPST start menu folder and open the "PDC" application.

    9. Go to the Device dropdown, there should be an item named "Qualcomm Wireless HS-USB Ethernet Adapter 9091". This is your phone, select it.
    1633496853860.png
    10. This is what you should see. Notice how only the original carrier's (T-Mobile) modem profile is loaded into the phone's modem. Pretty lazy if you ask me.
    1633497146862.png
    11. Now you will need some modem profiles to load into your phone! As a little starter pack, here are a few carrier modem profiles for US, Canadian and Korean carriers. Download them here (these are only for the G8/G8x/G8s! Will not work with other devices!!!!!!). I have extracted these from my phone's modem_a partition using QFIL Partition Manager with the LG SD855 firehose, and these are present in the modem_b partition as well. LG left all of these profiles inside the phone but only actually loads one of them into the modem on carrier models....

    These profiles may also work on the G8x, V50, and G8s since those phones have the same SOC as the G8, and by extension the same modem chip.

    12. Once you are ready, press the Load button and navigate to whichever carrier profile you want to add, I will load AT&T as an example. After going inside the folder for the carrier you want to load, there should be a file named "mcfg_sw.mbn". This is the profile. Don't bother adding any profile that has "row" in it's name, those usually don't give you support for VoLTE.
    1633498811451.png
    13. When you are ready, click Open and your carrier profile will be loaded into your phone! You can go and add as many carriers as you want, I loaded all US and Korean, and some Canadian carrier profiles into my G8.

    Do not load the same profile multiple times, this may cause issues with VoLTE and cell connectivity.
    1633501377502.png

    14. When you are done, go back to the LTE Data Test menu and set the tethering mode back to Android. Your phone now has VoLTE support for the carriers that you loaded into it!

    If you have another Qualcomm LG device, you can also follow this guide, you just need to enter the HiddenMenu dialer code specific to your device, and have carrier config files that are either specifically for your device, or from another phone that has the same chipset as your device* (*may or may not work).

    Here's AT&T VoLTE working with a Tracfone AT&T sim card on my previously incompatible T-Mobile G8:
    1633502003068.png
    1633502017259.png

    Hope this guide has helped you guys!
    1
    If it's anything like the Sprint V50, see if 5689#*820# works. But I suspect that even if it works, there won't be a Field Test option.
    Yeah, same result.

    If I use *#*#7262626#*#*, upon pressing the last * the code disappears and I'm still on the dialer.

    1
    Its weird, as far as I can tell... my device has VoLTE enabled on Tmobile, eventhough its DEFINITELY a Sprint model. Aside from that, I use Google Voice, which essentially lets me make calls and use data at the same time anyway.
    1
    On my Sprint G8X on 20p, simply replacing abl_a and abl_b with the special one used for BL unlocking made my phone think it's a T-Mobile one and enabled Field Test in the HiddenMenu. It's not necessary to do the BL unlock itself if you don't need it. Just thought I'd mention it in case anyone wants to try this on a Sprint phone.
    1
    That's too bad, but makes sense since the abl came from an 850.
    I wonder if you can use abl files from a different branded or unbranded V50? I'd think if you're not planning to BL unlock, you wouldn't need it to be an engineering abl.
    Looks like it's unfortunately still a no-go for the Sprint V50.

    Even after putting in the engineering abl file to make it look like an LM-G850, the 546368 dialer code still doesn't work (tried 850, 450, 820, 500 for model numbers) while the Sprint alternative code 5689#*850# still gives the same options as out-of-the-box with no Field Test.

    So I guess unlocking the bootloader and root access (to replace op partition files after which the 546368 code will work) are still needed for this particular model.

    Just to clarify, it's whats in the OP partition that will (or won't) allow those dial codes to work. And yes, the engineering abl, being from a specific model / variant of android, will almost always mean the device won't boot when it's flashed to the abl partition.

    So, if yours booted with it, and it seemed to somehow allow additional dial codes to work, then your OP partition somehow got the message it was a different variant device, and made them available. That's unusual, quite rare. Trying to repeat that with various other abl partitions from other devices / android versions is almost guaranteed to be a futile endeavor.

    The best way to do this, as mentioned, is to use the US open OP partition, and make sure the totc file is set to your specific variant (of course). Then the phone will act / be much like the US Open variant does, have volte and vowifi, less bloat, etc.

    But to get to that point, yes, bl unlocked and root / twrp needed.

    cheers