Successfully activated OnePlus 7T (Android 11) on US Mobile - Super LTE (Verizon)

US Mobile recently rolled out pooled plans that are using Verizon network.

The price, for whatever reason, is cheaper than US Mobile GSM that uses T-Mobile network - in Oregon for unlimited talk/text + 1GB, the total is $16.48 vs $11.48

The phone I have is T-Mobile version of OnePlus 7T (HD1907) running Android 11 (2021-06-01) with the stock unrooted ROM.

Whenever I tried to transfer the number or when the help desk was checking the IMEI number, it would always state that the phone was incompatible. The reason being is that Verizon has not certified a bunch of OnePlus phones as compatible with their network, even though phones are technically compatible.

In the same account, I also have a second phone (Google Pixel 3a XL) that is already using the pooled Super LTE.

Here is what I did to get everything up and running:

1. Activated VoLTE using instructions from https://nerdschalk.com/how-to-enable-volte-and-vowifi-on-oneplus-7-pro/I was worried about downloading and installing some random APK, but this file is also mentioned on xda-developers forums Supposedly, this does not properly or fully activate VoLTE, but after following these instructions, I was able to use the second phone sim card to dial and receive calls. There was an issue with the text messages.
2. Number transfer tool did not allow me to submit the request, because the phone was supposedly incompatible. Using Firefox with dev tools opened, submitted the phone transfer request using info for the OnePlus phone, however with the Pixel IMEI number. Request failed, because the Account number and PIN do not match the IMEI number.
3. Using the Firefox dev tools, I selected the submitted request in the Network tab and used the option to edit and resend the request. The only thing I changed, was the IMEI number. Request went through and returned 200 message!
4. Within 30 minutes, US Mobile sent me a message stating that my device does not contain HD Voice feature, which is required for the black, Super LTE sim card
5. Using the GSM card, I took a screenshot of the setting that became available after step 1 and explained that phone works fine with another activated Super LTE sim card. Two more times, reps kept telling me that the phone was incompatible, but when I asked for an explanation on why the second sim card worked, they finally took care of the transfer
6. After adding the new black Super LTE sim card, I could send and receive calls without issues. Text messages either were not delivered or were stuck with sending status. Using the info from this other post, I contacted support via chat and asked to activate CDMA-less feature. They did that and also verified that HD Voice Calling is enabled on their end.
7. The missing SMS messages went through and everything looks fine! HD+ icon is displayed next to the call timer https://i.imgur.com/66mdHOG.png
   Even the Visual Voice Mail works without issues.

NOTES:

• HD Voice Calling is the Verizon's implementation of VoLTE, so in my case these terms are interchangeable
• There are some instructions that have steps on making further changes using EfsTools, however to get it working properly, I needed to download and install sketchy (and infected according to VirusTotal) drivers, so skipped that all together
• Some reported that HD Voice Calling feature gets disabled after Android update, so I'll have to keep an eye on that.
• For some reason, VoLTE setting is not visible when Super LTE sim card is used, maybe because it is required?
• There are reports of issues with calls/text to/from iPhone devices when using CDMA-less phone, but it was supposedly fixed by Verizon.
• I'm fairly certain that the current bill does not have the correct regulatory cost fee
• Some users reported that Verizon can certify individual phones as HD Voice compatible, but it would require a trip to Verizon store and possibly becoming Verizon customer.
• Send me a message if you want a referral link to the US Mobile, which should give both of us a discount.

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This took quite a lot time to read numerous posts, talk to the support and hack my way through the US Mobile workflow, but having two lines for $20.96 total in my state with unlimited talk/text and 1GB data (can always add more data for $2/GB if needed) is a pretty amazing deal. Will see how long this will last.