[LG G8X ThinQ Questions & Answers] foxxyman:
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... :D

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...