Stock voicemail GUI stopped activating when moved from Pixel 5 to Pixel 6a

tapedisp

The other week, I moved my T-Mobile prepaid SIM card from my GrapheneOS Pixel 5 to a newly-installed GrapheneOS Pixel 6a, but Visual Voicemail in the stock dialer program doesn't work in the 6a (although it did in the 5). Specifically, it says it can't "activate".

I've spent many hours trying various settings changes, 5G vs. LTE, WiFi vs. mobile data, talking to T-Mobile customer support (telling them I had a Pixel 6a, but not about GrapheneOS), etc.

I also temporarily installed GrapheneOS's Google Play store support, and the T-Mobile Visual Voicemail app, and confirmed that does work. After removing the T-Mobile app and the Google Play support, Visual Voicemail in the stock dialer still can't activate.

When I installed GrapheneOS on the Pixel 6a, I also restored a SeedVault USB stick backup from the Pixel 5, from the installer.

Both Pixel 5 and Pixel 6a are using the stable channel of GrapheneOS.

I didn't have the SIM card in the phone at installation and first boot time -- I moved it later, after I'd confirmed everything else worked.

At the time I turned on the 6a with the SIM card in it for the first time, a text message came through from T-Mobile, saying "There's a new version of the Visual Voicemail app available now. In order to check your voicemail messages, you need to download the latest version of the app at t-mo.co/VMMtmobile".

I'm not familiar with the technical details, but I wonder whether I still have some wrong setting, or my phone wasn't provisioned/configured correctly for the carrier (T-Mobile customer support said they were having an hours-long "system upgrade" at the moment I moved my SIM), or T-Mobile has simply set things up to refuse to work with the stock dialer Visual Voicemail when it thinks the device is a 6a (but not when it's a 5).

I actually hate receiving voicemail, but I will hate it a little less if I can get the 6a working as well as the 5. Ideas?

brawfx

I had a Pixel 5 with GrapheneOS and moved to a 7A. VVM worked, and still works, on my Pixel 5, never could get it to work on my 7A. I've seen other reports of people having issues with the Pixel 7 as well. I tried everything I could find online, called T-Mobile, swapped the SIM back and forth from my 5 to 7A. Nothing worked.

After factory resetting my 7 and checking every setting, the only differences between the two phones, besides the actual phones, was the Carrier Settings Version. Makes sense, but also makes me think T-Mobile has made a choice to not allow it to work on certain phones in order to push their app on us.

tapedisp

Thanks, brawfx. That sounds plausible, but I hope you're wrong. Not only would it be sneaky behavior inconsistent with the warmer-fuzzier-pinker image that T-Mobile seems to want, but it's wasted many hours of my life after customer service was given an opportunity to tell me that they'd disabled it.

brawfx

tapedisp I had the latest GrapheneOS (13) installed on my Pixel 5 and Pixel 7A. I swapped the same SIM card back into the Pixel 5, and VVM works with the stock AOSP Phone app. Both phones are unlocked, purchased directly from Google's store. When I setup my 7A, I did restore with Seedvault from my 5 backup, and just to see if something got screwed up in that process, I factory reset my 7A and did not restore anything, and tried VVM again. Still didn't work.

I did talk to T-Mobile to see if we could get it working, and they had me try some things I had already tried. In the end, they suggested I download their T-Mobile VVM app and said they cannot guarantee VVM to work on all Android phones.

Same OS, same stock Phone app, two different phone hardware versions. Unless I am missing something, the carrier configs are the only differences outside of the actual hardware.

I am speculating since I have never figured out the solution, but having two Pixel phones running GrapheneOS and one works helps to narrow down the issue. I also just upgraded the 7A a few moments ago to GrapheneOS 14, and still no go on the 7A.

Pixel 5 on 13 - Carrier settings version
tmobile_us-44000000135
mcc 310 mnc 260
2023-04-14

Pixel 7A on 13 - Carrier settings version
tmobile_us-44000000014
mcc 310 mnc 260
2023-04-14

Pixel 7A on 14 - Carrier settings version
tmobile_us-50000000019
mcc 310 mnc 260
2023-06-30

tapedisp

Thank you for investigating and the info. Here's mine:

Pixel 6A on 13 (stock VVM doesn't activate) - Carrier settings version
tmobile_us-50000000034
MCC: 310 MNC: 260
2023-06-30

I've heard T-mobile has/had a team to escalate issues that are mentioned on Twitter. I wonder whether that's the only way to get a knowledgeable and straight answer from them. (CSRs might be told to have people install install the T-Mobile VVM app, but not know fully why.)

Related: I wonder whether T-Mobile would have any interest at all in being seen as the most responsive carrier for GrapheneOS in the US. Not just for this problem, but ongoing. (I've also seen problems like texts delayed, calls not ringing through, and I'm sure others will come up.) GrapheneOS is one of those less-common things that many people use for reliability and trustworthiness, not as a techie/hobby thing, so a supportive carrier would be a nice match.