Ok. That's super helpful to have a solid root cause. Again, I very much appreciate the help.

And checking the device page for the 3a, that's literally the only thing with an X. Lol.

At this point, I think trying Lineage or Graphene probably won't be helpful from a diagnostic standpoint. If I find that one of those supports VoLTE on the 3a, I might switch to that as a daily driver at least until Ubuntu Touch supports VoLTE on the 3a.

And in the meantime, I'll look more thoroughly at the thread you shared and see if there are ways in which I can contribute to the effort to make VoLTE work on the 3a.

Thanks again!

*Oh, I just saw the edit. Hmmmm! The plot thickens. That's especially surprising given that the device page indicates VoLTE isn't supported. Maybe there's just a difference between Australian VoLTE and U.S. VoLTE (I said North America above, but I'm specifically roughly smack dab in the middle of the contiguous 48 of the U.S.) such that UT works fine on the 3a with Australian VoLTE.

I also ran across this page from the Google support site that also seems to have some relevant info.

Anyway, lots of learning to be done here. I'm definitely a lot more in the know about my options than I was previously. Thanks so much!

@moem Thank you!

So, that got me what I needed to return to stock firmware and... I'm a bit disheartened to see the stock firmware can make calls just fine. Just because that means Ubuntu Touch, at least on that device and with the particular carrier I'm with, likely isn't an option for the moment if I want calling/texting.

I might try Lineage or Graphene or something just to get some additional data. I'd still prefer to switch back to Ubuntu Touch for my daily driver if I can. (Mostly because -- although I haven't actually started writing UT apps yet -- it seems way easier to do on UT than any particular flavor of Android.)

If there's anything else anyone can suggest to try or anything for purposes of getting more information or solving the issue UT has, I'm definitely open to that.

Just because this is probably helpful info, I'm on T-Mobile. (I'm grandfathered in on a super cheap prepaid plan and kindof don't want to give that up if I don't have to. Though, T-Mobile is making it clearer and clearer that they don't want me on that plan and they're making it harder and harder to even use it. Heh. Maybe switching plans is in the cards for me anyway, but anyway.)

Thanks again for the help! I'm at least glad to know more about this situation!

@rocket2nfinity said:

Boot into UT recovery.

I'm probably just being dense, but I didn't know this was a thing and I have no idea how to get into UT recovery. Can you (or someone) gently nudge me in the direction of a guide or anything? My google-fu is failing me and I'm not seeing anything on the phone (in the settings or the long-press-power menu or anything) that indicates it'll do that.

@arubislander said:

Did your carrier completely switch over to VoLTE and switch off 2g/3g for calls? That would explain the sudden inability to receive or place calls.

In the "cellular" section of my settings on UT, under "connection type", I see "2G only (saves battery)", "2G/3G", and "2G/3G/4G". Also, in the "Carrier & APN" section, it identifies the network as of type "4G calling (VoLTE)". Am I wrong to think that all means that my phone appears to support VoLTE properly?

Googling (well... DDG-ing, but who's counting?) a bit, I found this post. I'm not 100% sure whether that post is referring to VoLTE roaming specifically or whether what they're saying there applies to the 3a even on my carrier's home turf. (And I'm confident I'm well within the network area for my carrier, not in roaming territory.)

But that post also indicates that the only real way to test whether that specifically is the issue is to try the latest stock firmware, so it seems like my plan for an experiment was on-track. I'll definitely report back with results when I have them.

Thanks both of you! Definitely appreciate the help. I'm definitely not as well-studied on cellular sort of technologies as folks here are, so the expertise is extremely appreciated.

This is a super long story, but I'll try not to go on too long.

My Pixel 3a running Ubuntu Touch 24.04 (24.04-1.3) abruptly stopped being able to send/receive texts/calls a few weeks ago. And it was unable to connect to my carrier's network.

I took it to my carrier and got a new SIM card, after which it was able to connect to the network (it shows my carrier's name in the "network" section on the swipe-down-from-top menu), but it still can't send/receive texts/calls. (Also, a borrowed SIM card for a different carrier -- but which happens to use the same network of towers as my current carrier -- didn't work when inserted into my phone.)

Mostly just for troubleshooting reasons, I'm looking to return to the stock firmware. (Given that it worked fine and abruptly stopped, I'm guessing calls/texts won't work on the stock firmware, but that'll at least be pretty solid confirmation that it's a hardware issue. If somehow it does work on stock, I'll probably try returning to Ubuntu Touch and see what happens.)

I've got developer mode enabled on my phone, and I've got USB in "File Transfer" mode. But adb reboot bootloader gives me Failed to write reboot parameter file: Permission denied. I think this is an error from the phone, right? Not an "ADB can't connect to the phone" error but more of an "ADB told the phone to reboot into the bootloader, but the phone responded with this message" sort of error.

Am I wrong to assume that adb reboot bootloader should work with my phone when it's running Ubuntu Touch?

That's basically my question. Thanks very much in advance for any assistance you can provide!

Edit: Oh, forgot to mention the Google "Android Flash Tool" that runs in the Chrome browser doesn't have any better luck than ADB.