Hi All.
I've had an X10 mini pro on T-Mobile UK for nearly a year, and love it, but I am faced with a problem:
At work, I get absoluteley no signal. However, there are Wifi networks everywhere that are freeley available. It seemed logical to me that I aught to be able to get my phone to use those wifi networks to obtain a signal, so I did some research and found this generally to be reffered to as UMA (Unliceneced Mobile Access?)
For anyone who's coming across this technology for the first time, this is a facility which allows your mobile phone to use wifi connections as a backup for service signal, and switch seemlessley between them for use on calls (through your regular phone number [NOT VOIP!]) and texts.
I've read a lot of conflicting oppinions and statements on this, and wanted to ask here (In a place of expert knowledge and understanding) what the real truth is behind all this.
1: Is UMA a hardware or software based tool?
-I've heared numerous statements on this, including:
a) "Your phone can not do this if you don't have the correct hardware"
b) "The standard hardware (provided you have wifi access) is all you need, only the software needs to allow support"
C) "You need sufficient wifi technology AND the correct software to enable this"
Which is true?
2: "Service Providers are holding back on UMA support as it removes their justification for charging the user for calls"
- I've seen this in a few places, but it doesn't make sense to me. Sureley, despite the fact that the call is connected by a wifi signal, it still needs to find its way through a telephone exchange. Telephone exchanges cost money to maintain and manage, so that can't be right? can it?
- If anything, sureley this would give service providers a competative advantage as they can guarentee better signal coverage. It would seem more logical to me that the issue is less with the hand set, but with the providers managing the incoming and outgoing call data via the wifi network?
3: "UMA is/isn't supportend on android version X.X"?
- Again, I've seen conflicting info on this. What's the score?
Thought this was the right place to discuss all this and find the real truth behind UMA. My final question of course being:
4: Is there a UMA app or method by which I can use wifi as a signal backup? If not, is anyone looking into it and how soon may users see the benefits?
Appreciate any light that can be shead on this to dispurse the smoke and mirrors that seenm to surround it.
Thanks,
Oliver
hmmm
Supprised noone's responded to this... did I miss something?
In the USA, T-mobile has an app that does this. T-mobile USA uses the term wi-fi calling.
Is there such a thing in the UK? I know that the Optimus T (essentially the same as Optimus One) has this ability. I found this list of phones that work with this feature on T-mobile USA.
Phones that can make use of this new feature:
Blackberry 8520
Blackberry Bold 9780
Samsung Vibrant (SGH-T959)
Samsung Vibrant II (Galaxy S 4G)
LG Optimus T
myTouch 3G Slide
myTouch 4G
Motorola Defy
Motorola Cliq 2
Motorola Cliq XT
Sidekick 4G
G2
G2X
Nokia Astound (C7-00)
Nokia Mode (E73)
Samsung t339
Some other older android phones can work as long as the app has been ported for the device. Very YMMV
Click to expand...
Click to collapse
I do not think your phone is available through T-mobile USA, so it is not on the list. Someone figured out how to bring wi-fi calling to non-tmobile Roms for the Optimus T/Optimus One phone. http://forum.xda-developers.com/showthread.php?t=1116268 However, I am fairly certain that this type of app needs the cooperation of your carrier to work.
Action_Man_1 said:
Hi All.
I've had an X10 mini pro on T-Mobile UK for nearly a year, and love it, but I am faced with a problem:
At work, I get absoluteley no signal. However, there are Wifi networks everywhere that are freeley available. It seemed logical to me that I aught to be able to get my phone to use those wifi networks to obtain a signal, so I did some research and found this generally to be reffered to as UMA (Unliceneced Mobile Access?)
For anyone who's coming across this technology for the first time, this is a facility which allows your mobile phone to use wifi connections as a backup for service signal, and switch seemlessley between them for use on calls (through your regular phone number [NOT VOIP!]) and texts.
I've read a lot of conflicting oppinions and statements on this, and wanted to ask here (In a place of expert knowledge and understanding) what the real truth is behind all this.
1: Is UMA a hardware or software based tool?
-I've heared numerous statements on this, including:
a) "Your phone can not do this if you don't have the correct hardware"
b) "The standard hardware (provided you have wifi access) is all you need, only the software needs to allow support"
C) "You need sufficient wifi technology AND the correct software to enable this"
Which is true?
2: "Service Providers are holding back on UMA support as it removes their justification for charging the user for calls"
- I've seen this in a few places, but it doesn't make sense to me. Sureley, despite the fact that the call is connected by a wifi signal, it still needs to find its way through a telephone exchange. Telephone exchanges cost money to maintain and manage, so that can't be right? can it?
- If anything, sureley this would give service providers a competative advantage as they can guarentee better signal coverage. It would seem more logical to me that the issue is less with the hand set, but with the providers managing the incoming and outgoing call data via the wifi network?
3: "UMA is/isn't supportend on android version X.X"?
- Again, I've seen conflicting info on this. What's the score?
Thought this was the right place to discuss all this and find the real truth behind UMA. My final question of course being:
4: Is there a UMA app or method by which I can use wifi as a signal backup? If not, is anyone looking into it and how soon may users see the benefits?
Appreciate any light that can be shead on this to dispurse the smoke and mirrors that seenm to surround it.
Thanks,
Oliver
Click to expand...
Click to collapse
Try this solution, T-Mobile and Orange have done a deal where they can use eachothers signals, go back to netwoork settings and you should find " T-Mobile-Orange 3G"... Connect to that and it may work.
It seems that T-Mobile and Orange both have very bad coverage compared to other competators.
Related
Hi Y´all.
Did a search on this without any luck. There isn´t any forum specifically for Huawei U8650 (sonic) and i think this might be an android issue.
I bought this phone for my stepdaughter on her 13´th birthday and i can´t for the life of me figure out how to acheive data connection.
This is what i have tried:
1: The SIM-card used for test is my own card, normally running flawlessly in my Desire HD. It therefore stands to reason that the there is no problem with the service provider.
2: SMS and voice dial generally performs as expected. One odd thing strikes me though:
Any bog standard sms from another phone is recieved as always.
The service provider has a "setup by sms" service and there is a setup for the Sonic as well. That sms isn´t recieved.
Can an android phone be locked to a fixed country? has anyone ever heard Huawei doing such a thing ?
The phone is tested in Greenland but was bought in Denmark.
The phone was not bought through a service provider but a bog standard electronics webshop. thus - no contract.
2g & 3g network are enabled.
Access points for MMS & GPRS are set up as instructed by service provider.
Phone has been set up to choose automatically between 2g & 3g network allthough fixed 2g & 3g connection respectively has been attempted.
The phone has been for a check up under guarantee - came back with a clean bill of health.
Here´s what really confuses me:
When i scan for available networks the phone can actually see both 2g & 3g network
Pretty much the only thing that i haven´t yet tried is rooting the handset and trying another rom.
I´m going to travel to Denmark in a couple of months and am considering bringing the handset with me for further testing.
There it will also be possible to show up in person at the store and get them to show me it works. I am therefore not inclined towards rooting since it, most likely, will be a guarantee "gotc`ha"
please help - my mental health is at stake :silly:
Regards
ELO
Hi folks,
I'm looking to possibly switch to T-Mobile, but I know that coverage is spotty in my home town. (I don't go home often... Maybe once or twice a month for a weekend)
Because of the spotty coverage, wifi calling is a feature of T-Mobile that is very appealing to me, but I've been hearing rumors that their wifi calling feature doesn't work unless you purchase the phone directly from T-Mobile (which obviously cannot be done).
However, I do remember seeing a screenshot of the Xperia Z5 Compact's wifi calling settings and there was a tab listed for T-Mobile. Now why would a phone include wifi calling options for a specific carrier if that carrier refuses to support that phone?
Now let's say there is no way to trick the Z5 into letting me use wifi calling on T-Mobile... I read an article stating that CM13 will support T-Mobile's wifi calling. If CM13 was developed for the Z5C, would that do the trick?
Praying that someone with some more experience can shed some light on this matter. Is there any hope for me?
T-mobile announced that they'll be giving mini towers to customers for free (that's not wifi calling but an actual LTE tower for your house that uses your internet connection) so you can just call them up and ask when they'll start sending them out.
Does it just generate an LTE signal? That works well if the phone had working T-Mobile voice over LTE; which i'm not sure it would if I purchased an unlocked model. That router would be great for my home, but I'm concerned for other areas of my hometown, where I actually would need service (for example: car accident). If I could connect to a local coffee shop's wifi connection to make calls; that would make my life so much easier. I would hate to only have service in my home because that would make me feel bound to my house.
JGoldz75 said:
Does it just generate an LTE signal? That works well if the phone had working T-Mobile voice over LTE; which i'm not sure it would if I purchased an unlocked model. That router would be great for my home, but I'm concerned for other areas of my hometown, where I actually would need service (for example: car accident). If I could connect to a local coffee shop's wifi connection to make calls; that would make my life so much easier. I would hate to only have service in my home because that would make me feel bound to my house.
Click to expand...
Click to collapse
It's only phone based: https://support.t-mobile.com/docs/DOC-24269
FYI, I did use T-Mobile on an unlocked, unsupported phone last year for few months and I don't recall ever not having phone signal. Data is another story but calls were always available and I do travel a lot across the world. Their international data is pure BS - it just doesn't work.
And finally, the T-Mobile WiFi calling menu you saw is for the old T-Mobile in the UK that has now been merged into EE. You can flash that firmware but it probably won't work with the USA version depending on what moron wrote the integration and how much configuration data they hardcoded in the app or if it works it might be connecting to a UK gateway.
weasal said:
It's only phone based: https://support.t-mobile.com/docs/DOC-24269
FYI, I did use T-Mobile on an unlocked, unsupported phone last year for few months and I don't recall ever not having phone signal. Data is another story but calls were always available and I do travel a lot across the world. Their international data is pure BS - it just doesn't work.
And finally, the T-Mobile WiFi calling menu you saw is for the old T-Mobile in the UK that has now been merged into EE. You can flash that firmware but it probably won't work with the USA version depending on what moron wrote the integration and how much configuration data they hardcoded in the app or if it works it might be connecting to a UK gateway.
Click to expand...
Click to collapse
It's not that I think the phone will not have service because it's unlocked. T-Mobile just doesn't have great coverage in my hometown area at all. I did the Test-Drive a couple months back and remember getting 0-1 bars at all times... never holding on to a signal long enough to make a single phone call or send a text message. Thanks for the insight into the T-Mobile - EE thing. I didn't realize that. It would be lovely if it did work in the USA but I doubt it The T-Mobile Nexus 5 (arguably one of the most modded phones out there) never got t-mo wifi calling so I doubt this will.
Thank you!
Just so you know, I flashed to EE (even though technically I'm on MetroPCS which is a T-Mobile subsidiary), and I couldn't find that screenshot in any of the settings menus, nor could I locate it via "settings, under device, call. UK EE" as someone suggested in that thread. I do have a "Device Connection" menu and a "Call" menu, but they're separate menus not nested in one another. And I can't find any menu or option that says "UK EE".
So, it sounds like no one can find any Wifi calling toggle in any settings menu, correct?
nnotis said:
So, it sounds like no one can find any Wifi calling toggle in any settings menu, correct?
Click to expand...
Click to collapse
A couple people have mentioned seeing it...someplace. One person said he saw it under the pencil looking icon in the drop down shade, but I've never been able to locate it up there no matter what firmware I've flashed too. It appears to be pretty elusive.
Adrift98 said:
A couple people have mentioned seeing it...someplace. One person said he saw it under the pencil looking icon in the drop down shade, but I've never been able to locate it up there no matter what firmware I've flashed too. It appears to be pretty elusive.
Click to expand...
Click to collapse
It's probably checking for some condition to show the menu.
If you extract the EE firmware you would probable be able to do a text search for T-Mobile and find the apps that have that then decompile the one that sounds like the most likely to have the functionality (probably one with the word customization in the name) and check the logic which enables the functionality and even change and re-compile it. You would also be able to see if it connects to a specific gateway for the wifi calling and if so try to change that too..
Theoretically a company won't spend the money to develop different Wifi calling mechanisms for different countries and thus it should work but then again...
weasal said:
It's probably checking for some condition to show the menu.
If you extract the EE firmware you would probable be able to do a text search for T-Mobile and find the apps that have that then decompile the one that sounds like the most likely to have the functionality (probably one with the word customization in the name) and check the logic which enables the functionality and even change and re-compile it. You would also be able to see if it connects to a specific gateway for the wifi calling and if so try to change that too..
Theoretically a company won't spend the money to develop different Wifi calling mechanisms for different countries and thus it should work but then again...
Click to expand...
Click to collapse
I wouldn't know how to begin to do all of that.
Adrift98 said:
I wouldn't know how to begin to do all of that.
Click to expand...
Click to collapse
You can follow this to extract the system partition (system.sln) and get it's contents to your hard drive: http://forum.xda-developers.com/showthread.php?t=1723284
Then you can use your file explorer (on Windows or whatever your OS is) to search for a text string (make sure you tell it to look only inside *.apk to avoid getting too many results). Once you find the apk files that could be what you need you can then use this: http://www.decompileandroid.com/ to decompile the apps so you get source code.
From then on it's a bit trickier, you'll need to make your way trough the configuration and maybe even the code to figure out where they store the connection info or what exactly do they connect to (it looks like the app uses your sim card to authenticate so that shouldn't require any tweaking).
Or you can just wait and hope this is true: https://support.t-mobile.com/thread/81359 or maybe it's already in M : http://www.phone-probe.com/android-m-features-native-wifi-calling/
Oh is that all? Simple.
It might be easier to just locate the apps needed for US T-Mobile wifi calling from another phone and install them on a z5c with EE firmware since the core OS code needed would be provided by the EE firmware and the US specific stuff will come from the apps.
This has a list that might actually be complete: http://forum.xda-developers.com/showthread.php?t=2302313 and you can ignore any jar files that are listed since that should come with the EE firmware.
The fact that there is a z5c firmware that supports Wifi calling is what's important here - you have all the proprietary and OS stuff baked in, you just need the US specific bits/configuration.
Unlocked phones are becoming more popular. I am looking at getting a new phone/network, as I recently moved and now have very poor service at my house (U.S.).
Currently, I have a Verizon iPhone 5s (A1533) (that I purchased via VZW and used on their network for a couple years). I am now using this phone on T-Mobile. However, my 2G/3G bands seem to be somewhat weaker in some areas and I cannot do wifi calling.
I would like to get an unlocked phone and have full-service on a network.
I would like to switch to Android, specifically a Sony Xperia XZ1/Compact. Therefore, I would like a GSM capable network (AT&T and T-Mobile -- and their affiliates), but otherwise I don't care too much about carrier as long as it works well. I have done quite a bit of research, but am having a hard time finding anything super-informative and definitive. I have come across < spectrumgateway > and < willmyphonework >, which provided some information, but I'm still a little confused on to what extent each phone/network combo will work.
I've noticed FaceTime on my iPhone works (but can only call other FaceTime/apple devices like that). Is there an app or anything for android that always fill in wifi calling? I mean, the wifi calling allowed in service providers' firmware is essentially that, right? So can a third party item allow this or root the phone to allow it or something?
Is there any network I can use an unlocked Sony phone on and get full-service?
I need a good phone connection for work. I am supposedly well within all service providers' networks (per coverage maps), both voice and LTE, but without the carrier firmware that seems to, essentially, be false. I find this very ironic and frustrating, given that many carriers are now advertising "BYOD" plans (T-Mobile's entire U.S. ad campaign is based around this and unlimited services "the Uncarrier").
Thanks in advance!!
1230m said:
Unlocked phones are becoming more popular. I am looking at getting a new phone/network, as I recently moved and now have very poor service at my house (U.S.).
Currently, I have a Verizon iPhone 5s (A1533) (that I purchased via VZW and used on their network for a couple years). I am now using this phone on T-Mobile. However, my 2G/3G bands seem to be somewhat weaker in some areas and I cannot do wifi calling.
I would like to get an unlocked phone and have full-service on a network.
I would like to switch to Android, specifically a Sony Xperia XZ1/Compact. Therefore, I would like a GSM capable network (AT&T and T-Mobile -- and their affiliates), but otherwise I don't care too much about carrier as long as it works well. I have done quite a bit of research, but am having a hard time finding anything super-informative and definitive. I have come across < spectrumgateway > and < willmyphonework >, which provided some information, but I'm still a little confused on to what extent each phone/network combo will work.
I've noticed FaceTime on my iPhone works (but can only call other FaceTime/apple devices like that). Is there an app or anything for android that always fill in wifi calling? I mean, the wifi calling allowed in service providers' firmware is essentially that, right? So can a third party item allow this or root the phone to allow it or something?
Is there any network I can use an unlocked Sony phone on and get full-service?
I need a good phone connection for work. I am supposedly well within all service providers' networks (per coverage maps), both voice and LTE, but without the carrier firmware that seems to, essentially, be false. I find this very ironic and frustrating, given that many carriers are now advertising "BYOD" plans (T-Mobile's entire U.S. ad campaign is based around this and unlimited services "the Uncarrier").
Thanks in advance!!
Click to expand...
Click to collapse
[I can't post links yet, so the article is called "Sony Xperia XZ1 & XZ1 Compact Support T-Mobile WiFi Calling" by Alexander Maxham from < androidheadlines >]
Okay, so I found this article today. Can anyone vouch for/test this? This is the only source I've seen claiming that Sony certified the Xperia (both, XZ1 and XZ1 Compact) on the T-Mobile-USA network.
Edit 1: T-Mobile News ("tmonews") has an article titled "Sony Xperia XZ1 and Xperia XZ1 Compact debut with Android 8.0 Oreo in tow" where they state "Finally, Sony has confirmed to me that the Xperia XZ1 Compact has been certified to work with T-Mobile’s VoLTE and Wi-Fi Calling in the U.S.". Is only the Compact certified? Or was that just a typo/confusing bit?
I'm sorry if this wasn't in the right area, I googled up this same question and this board has it the most it seems. If its in the wrong area, please move the topic to the right area so I know where to ask next tome (or link and I'll delete this ((if possible)) and recreate).
I've been using PDANet USB Tethering for the last 3 years or so with Boost Mobile, Samsung Galaxy S3. My phone is showing severe signs of age and issues, and I'm having tons of PDANet related issues. I have unlimited 4G LTE data, but I can't use my wireless tether because the phone company detects it and stops it at 8GB where as USB tethering I've gotten 100+ GB in a single month no issues.
I'm looking for a new phone I can get, that I can somehow mask everything I do on it so that the phone company is unable to see what I'm doing on it, and won't be able to determine if I'm using my phone's wireless tethering features. I prefer a smartphone, obviously, cause I do take it with me where I go and like to have access to my apps. I'm inexperienced with installing ROMs or rooting, never figured out how with my S3 because all the topics are outdated and inaccurate and I only ended up damaging the phone trying. I've got about a week or two to find a new phone that will work with Boost Mobile. My current phone's network mode is CDMA/LTE/EVDO, just to give you an idea of what network I'd need to use for Boost (CDMA I guess?). I need 4G as well, it seems that 3G doesn't work at all at my location and I only get 1 bar of 4G LTE when I'm at home in a specific 3 inch by 3 inch space in my room that I have to tape my phone down to, but at least it works.
There's no other internet options available to me where I live, so my phone is my internet. Just to clarify before people suggest getting an internet service.
Just to be sure, I don't want anything made by Apple, but that should be obvious, posting in the Android forum.
I have found that Boost Mobile won't let me use anything but like 6 specific phones only. Two of the choices being the S7 and the S8.
I've done a search on Amazon looking for unlocked S8 phones, however the comments and reports all claim these unlocked devices are a lie and don't actually work with services they claim to, or have conflicting reports and such. I'm unable to find an Unlocked S8 for use with Boost Mobile.
I've found that I can edit the APN to add 'dun' to my type list, to bypass the data limit of Mobile Hotspot, however I am hoping that it doesn't also cause the company to start charging me hundreds of dollars a month. I want to make sure they can't actually see the traffic either, I don't want my ISP knowing what I'm doing online, because they will just turn around and sell every website I visit to third parties which is now a thing in the USA.
I'd rather Boost not know whats installed on my phone or what websites I visit.
Thread closed as per OP request.
I plan to keep updating this XDA forum thread with what I find out about this problem, potential solutions, and hopefully what solves it. Hopefully this will be useful to those with the same or similar problem.
Please excuse typos...
The Solution
The reality is, prevention is the best solution here, do a bunch of research to make sure you don't encounter this problem. Read the rest of the post to better understand.
Original
Thank you in advance for reading this and helping me. (I also posted this in r/LGG8X, and am posting it here because some people don't have accounts with both. The more people that see it, the better, if by chance someone has ideas, wants to help, and has time to post the ideas)
It seems like a lot of people are having this issue, so maybe someone might have an idea.
I bought this phone to replace my Xiaomi Mi 9 (which was on the fritz, turning itself off randomly), about 1.5 weeks ago. I did my research and reasonably concluded that this phone has LTE band 12 and VoLTE; also it would be foolish of LG to not to have that. I could not find the VoLTE or Wifi Calling switches anywhere in the settings app, or in the phone app. I then dialed " *#*#4636#*#* " which opened up the "Testing Settings" (as usual). I click on the "Phone Information" tab, scroll down and find both the VoLTE and Wifi Calling switches, which are, to my dismay, greyed out.
I called Ting and they said, (after getting the IMEI), that this doesn't have LTE band 12, therefore no VoLTE. That confused me, because like I said, my research before buying had already concluded that it has band 12. The Ting rep said that's all he could do for me, so we ended the call. I did another 30 mins of research, again concluded it has band 12 with VoLTE. I also called LG themselves, and the rep there confirmed that this phone has band 12 with VoLTE, they also said "we would be more than happy to verify that the phone works with you carrier through phone conferencing". I asked the rep about about the previously mentioned VoLTE and Wifi Calling switches being greyed out, and they said that's because the phone has those 2 capabilities, but the carrier has to enable them.
I really love this phone, especially in comparison to the Mi 9 (even tho the Mi 9 is a good phone). I love the software better (even with the weird quirks that it has), and the value proposition is quite good. I really don't want to have to get a 3rd new phone in one year. If anyone has any ideas/help that would be greatly appreciated.
Thank you
[Edit]: P.S. I think this is partly a problem with LG, and partly with the carriers. I suspect that LG messed up with the IMEI/etc and other important identifiers as to what the device is, what exact version (i.e. LM-G850UM, etc) of a particular model (i.e. LG G8X Thinq Dual Screen, etc). This leads to the cell carrier's infrastructure seeing this phone as incompatible (doesn't see LTE Band 12, when it really is. The cell carriers, (from my own experience with 2 Ting Reps, and from what others have said on other forum threads), can't or won't solve this problem, even tho it may be solvable. From what I have seen on other forums, some got it solved by the cell carrier entering codes on the phone and doing something on their side. If LG and the all the networks would talk to each about this problem and get it solved if possible that would be awesome...
Update - 11/04/2020:
It seems I unintentionally bought a G8X with the Canadian rom LMG850UM20e. I am doubtful, but is the hardware the same or similar enough to flash the USA unlocked rom LMG850QM? Or is there something else I can do to make the Ting network allow VoLTE? As far as I can tell, the Canadian model still supports VoLTE LTE Band 12, but correct me if I'm wrong.
Update - 11/05/2020:
Ting says that my phone has LTE Band 12 and therefore VoLTE, but that will only work on ATT. A bit confusing because (like I said) the particular rom on my phone is Canadian (LMG850UM20e), so why ATT? The explanation for that, it seems is that ATT, (and Sprint), and the unlocked Canadian version have the same sub-model: LMG850UM. The USA unlocked version has a different sub-model (LMG850QM), the rest of the world has yet another sub-model (LMQ850EMW). There are around 15 different versions it seems; see this reddit post on the different models: (can't post the link yet) title: "Hey G8X owner, what is the submodel number and regional code of your unit? And where did you buy it from? I am trying to complete this list, also relating to timing of security updates and Android 10 release." posted in r/LG G8X
It seems like all the versions (LMG850......) have the same hardware, the only difference are the roms, which seem artificially disable certain capabilities of the phone. I am pretty sure my phone would do VoLTE just fine on Ting (or most other carriers). The thing wrong here, I think, is that the IMEI and other specific identifiers of the phone artificially show that the phone does not have the functionality, so the networks don't enable it. It also seems like LG made an agreement or something with ATT as well as Sprint (separately), to release carrier-specific version (as most brands seem to do), and that the phone would fully work on their respective networks and MVNOs, at least the versions in the LMG850UM sub model group, and the USA unlocked sub-model group. LG and T-Mobile seem to have come to no such *official* agreement, unfortunately. I am wondering any of the versions work with T-Mobile and it's MVNOs out of the box, some *modifications* may have to be done in order to get it working on TM towers. There may also be unintentional bugs in some or all roms that are possibly causing, or more likely, adding on to the problem.
Obviously, I am still trying to find my around this problem. I'm considering flashing a USA unlocked rom (LMG850QM sub-model), though not sure if that's possible, or if it'll change what the IMEI and the other specific identifiers tell the cell carrier about compatibility. I also wonder if carriers have the ability to override the artificial restrictions. There is also one report of T-Mobile supposedly fixing the same/similar problem with Sprint for a customer, see u/Veshtarii's comments on this reddit post: (can't post link yet) title: "LG G8X unlocked models having issues with US carriers." Posted in r/LGG8X. Another reddit user used a cheap Tracfone sim card to make his phone work on T-Mobile: (can't post link yet) title: "Tutorial: How to Update eBay Unlocked ATT / AT&T LG G8x" Posted in r/LGG8X. I am unsure if he also has VoLTE working.
Update - 11/06/2020
I'm done with this... It is pretty much impossible. I commented on the "Tutorial: How to Update eBay Unlocked ATT / AT&T LG G8x" post, and the OP responded and said he can't get VoLTE working, even with doing that update. The only thing that could possibly work, is flashing the USA unlocked sub-model onto it. However I probably don't know enough to do it right, but the bigger reason is that it'll probably brick it. I've realized, and should realized when I was doing the research for a new phone, that ATT and TMO's VoLTE/Wifi Calling work differently. They both use propriety coding, which they license to each brand to use in the models they both come to agreement on, and a similar agreement with each MVNO under their towers. LG and TMO seem to have made no such agreement for the G8X, therefore in all practicality, no G8X will work on any of their towers. Also, I called H2O Wireless just to see if my phone works with them, but they said my IMEI is not compatible; so I'm not the Canadian model that I have works in the US at all, that makes me think that not even the versions inside each sub-model aren't even compatible with each other. There is that one situation I mentioned, where the person who was having problems with Sprint before the merger, took it to TMO after the merger and the TMO tech fixed it for him. But I think he must've been having a different problem, because his phone is probably still technically running on Sprint towers. Sprint made the agreement with LG, so VoLTE would work in that instance. Flashing is practically not a solution for most people.
I should've done more research than I did before buying the phone. That is the moral of this story; make sure you do all your "homework" before buying any phone anywhere but the shop of the carrier you are using (or plan to use). That leads me to my number one complaint with phone brands and especially cell carriers as whole: they make it incredibly annoying, often difficult, and confusing to find a compatible phone that isn't on the carrier store. And the problem with that is that everything in any carriers' stores is everything is stupidly overpriced, and then they get you hooked with pricey deals you don't want. If you're reading this, you're most likely like me, you know better than to spend more than you have to on a phone and plan in the carrier store, you know (or at least kinda know) how to get past that. I get that cell carriers want to make money, but I tell you, this is too far. Anyways, the point is, there is no immediate solution, in other words, your only worthwhile solution is prevention, doing a bunch of research. I'm done with this... I'm returning this phone and getting the vanilla G8...
I have the LMG850QM. It has no VOLTE icons while in call even if on band 12. It uses HD+ and that will be shown in dialer during call. Internet does work while in call so believe that it is working. The switches are on like yours but greyed out. Wi-fi calling does work. By turning on airplane mode and then turning back on wifi the dialer will show that calls are being made over Wifi. The OnePlus 6T has VoWifi icons in status bar and this phone doesn't. I will say that this phone gets service in buildings where neither of my 6t's would have service.