@atarilinux You don't need 5g yet, but eventually as they transition more and more bands to it, and the remaining 4g bands become too crowded. That is why I suggested the OP N10/N20/n200/N300 which are 5g capable.

As far as VoLTE, in the US, the device needs to be VoLTE capable, and if the device is not capable of reporting it's location directly to e911, then the user must register a service address with their carrier before VoLTE or VoWiFi will function. It will be quite a while before our e911 systems are upgraded across the board to make location tracking mandatory (because e911 was left to the counties to fund, and a good number of them do not have the resources to convert to an automated system).

You do need a phone that is carrier certified for Verizon or AT&T. T-Mobile just requires the device be capable. They do not keep white lists, only block lists.

A couple of thoughts:

The OP6/T was one of the successful models in the original VoLTE experiment. It did not receive the final version because the porter is in Ukraine and the port is effectively abandoned. The OP Nord N10 now has VoLTE (24.04-2 daily) and the N100 likely will (same porter). Perhaps an updated port for the 6/6T would be worth your effort, or one for the OP Nord N20/30 or 200/300 as they are 5G models

There is renewed effort to get SIP completely functioning and integrated into the dialer. If that effort is successful, the existing port of the P3a could still be useful as a VoIP phone.

Which brings me to heresy - use Droidian with SIP, or Mobian or PostmarketOS (patches needed with Mobian to match PMOS) as VoLTE is somewhat functional (a work in progress) with P3a and OP6/T.

And since Mobian/PostmarketOS is mainline, you could confer with Oren (Pinephone/tab porter) to see how to build a mainline UT port for either of those two models

@CyBerT Plenty. Here's one

https://www.getdroidtips.com/oneplus-6t-stock-firmware-collections/

Here's another

https://xdaforums.com/t/rom-stock-fastboot-op6t-stock-fastboot-roms-for-oneplus-6t.3862516/

If you still have UT Recovery flashed to your device, you can use that. Personally, I just use msmDownloadtool. Going back and forth between UT, Mobian, PostmarketOS messes with your partitioning. It is often best to just use the factory tool to reset it - especially if you haven't flashed a ROM before.

@vverve 2g is still up in a lot of areas with T-Mobile. 2g & 3g are still up if you live under the footprint of one of the Baby Bell regional carriers. They are small and slow to swap out their tower hardware.

@CyBerT The easiest way would be to use the MsmDownloadtool and reinstall OS9 as described in the OP6/T section of this forum.

You could also flash it by using fastboot since your installation is not corrupted.

@theprivacydad Flash a factory image using fastboot.

https://android.gadgethacks.com/how-to/complete-guide-flashing-factory-images-android-using-fastboot-0175277/

@mafman97 You can install Windows to a USB thumb drive and run MSMtool from that

There is also a linux method somewhere in the OP 5 or 6 forums, but results are variable.

@atarilinux That (VoLTE on P3a w/ Mobian) is with q6voiced and 81Voltd. Last I read it is broken again. Although, P3a is almost complete with mainline linux (especially with PostmarketOS - has patches not yet upstreamed). Might want to talk to Oren (maintainer of the Pinephone) if you want to try making a mainline port of UT for the P3a. OP6 is functional with VoLTE with mainline (with occasional hiccups) and OP6T can also call, but still has audio issues w/VoLTE last I read. Considering the OP6/6T is unmaintained with UT, it could benefit from a new maintainer - halium or mainline.

@atarilinux See mautrix-telegram at matrix.org

@atarilinux With the exception of VoLTE, the P3a with the current 20.04 port is the finest example of what UT on a phone can be. I wish you the best of success with your updated port. Join us in the NA Issues UT Telegram group, and you'll have testers waiting to help when the time comes.

@Joko If you are in North America, you should use 10.5.3. But if you are not, 10.5.2 is the correct version.

IRT your WiFi, in terminal check nmcli -g and nmcli -r and see if your WiFi is in an unmanaged state. You can also check WiFi with dialer code ##4636## using android, but not with UT

@FrostDaemon It might boot up correctly if you power off then try again. Same happened on the OP N100. Took two tries to get it to boot

@Joko Absolutely DO NOT re-lock the bootloader. UT is not set up for that, and you will likely brick your phone. Re-locking has been investigated, but it hasn't been a priority.

The 10.5.5 image is what the folks at xda-developers released for Android ROMs. Someone in the thread said it was good regarding UT. I just compiled my own since I've had to do this for other OnePlus phones as well. I do not have a place to host the re-compiled file I did. I am open to suggestions of where to put it if you do not wish to re-compile it yourself.

@Joko Did you just update to 24.04-1.0 ? My WiFi no longer works on that. Still does on 20.04 stable

If you have no audio at all, it is likely because the hooks in HAL do not match with the kernel you have. I would try with the patched 10.5.3 kernel.

@Joko Glad you got it figured out. Installer ran smoothly with no errors, and all hardware working on 10.5.5? Have you tried to activate VoLTE?, and how did that go?

Well that was a special level of hell... But, just as OP stated, using opodecrypt worked. For those with a Metro N100, you can just use this to flash to the global firmware. It is already patched:

https://mega.nz/file/8fhxkQoR#Yt1ZFJMXsY-wuQIhQ7ar8M_E6PN6wB9NixdPYtWzCQA

If you are using a T-mobile N100, you will still need to follow the guide here if it is still locked (T-mobile unlocked devices if requested at the time): The AT&T N100 (very hard to find) came unlocked and is the global model.

https://xdaforums.com/t/flash-global-rom-to-tmobile-metro-w-locked-bootloader.4387517/

You do not need to contact OnePlus for an unlock pin. Converting to the global firmware will allow you to unlock the device. You do have to use the patched msmDownloadtool to do it, or patch it yourself as described above

Once you have it flashed to global, unlock the bootloader, then on reboot enable developer options and use the UT installer. I set the options to repartition as OP did, and it failed. Retried without the partitions option and it worked - with the caveat that I had to run the installer multiple times because the connection to the server kept dropping. That might not happen to you. Also, the UT installer will error out with a message about setting slot A or B, and an error about the filesystem - hit ignore both times and it will still flash the device. Once again, it may take multiple tries to achieve success. But, when it boots, everything works, except VoLTE which I am troubleshooting.

Also, it does not work with a Verizon sim out of the box, but does with T-mobile.

@Keneda Just giving options. He wants no maps, no camera, etc. Some of UTs phone ports do not have working camera, but most do. Pinephone and Librem, as you know, have physical switches to disable camera, etc. He could just physically remove the camera from any phone as well, although that might have unintended effects depending on how it's wired.

@simply I would suggest a Pinephone or Librem 5/Liberty phone or one of the Mobian/Droidian or Postmarketos phones

@diddub Try Sapot browser, or one of the browsers available in SnapzOr

@jhayar0719 I have one, free, if you are in North America. Shipping and customs makes it not worthwhile to send overseas