VoLTE support progress

This has been resolved for me. VoLTE confirmed does work for T-Mobile and Mint as an MVNO in the U.S.
Phone calls are instantaneous for me. Thank you @joao.azevedo for the guides to complete this firmware upgrade.


@joao.azevedo, is the firmware upgrade on phones shipping now?


@joao.azevedo Would you also send me the guide. Then I’ll test it with Telekom Germany.

It might just be faster to send an email to support@puri.sm and follow their email formatting etiquette that is pinned on the front page of this forum.


Yes, I suppose if Purism wanted to make the necessary instructions universally available, they would just publish a document somewhere on one of their web sites.

I guess there is a reason for not making it universally available e.g. hard to cover all scenarios in a document that remains comprehensible or some scenarios that aren’t covered or significant risk of user stuff-up and brickage. Something?


ok, I wanted to answer to this yesterday, but things happen.

Yes, there is a more recent firmware version for the modems that we had in the last 2 - 3 weeks.

Yes, this new version of the modem firmware should start being shipped in new devices in the coming weeks.

Yes, it does help in several cases with VoLTE. But there are still some cases to figure out with some specific carriers.

This new version also improves the ability of the modem to wake up the Librem 5 from suspend when there is an incoming call.

And yes, we are working on a tool to make an update easier, with the press of less than half a dozen buttons.

Now for the “but” part:

  • We are still testing the tool for a person to update the modem firmware.
  • While the vast majority of tests/updates went without a problem, we did had in the early stages of testing 4 cases where the firmware update did not went well, with 3 of them some of the modem data was not properly backed up (and that seems solved now), and one case where the modem was almost trashed and had to be reflashed a second time.

Basically before considering releasing this tool “into the wild” and risk “opening the flood gates” we want to test this tool more, so that updating the firmware is safer and simpler. And check edge cases, because they exist.

Because, worse than not having VoLTE working can be having a bricked modem, and we want to avoid that. If a modem is bricked then the only options are;

  • Replacing the modem
  • Grabing a soldering iron and a programmer and doing something like this:

So for now while we are still testing this update utility, we would prefer to use it with support cases that have an actual issue that can be actually solved by this new firmware version.
And closely monitor the process with the user in case problems happen. And take the feedback from those cases to improve it.

EDIT: Added the part about suspend.


The expected delivery date of my phone is three days from now. I would have opted for a few weeks delay to have the up to date firmware if I was given that option. After all, what is a few weeks more when waiting for almost four years.

Maybe you could consider that option?


To emphasize this and the need to test the update utility and the firmware before releasing. We found a new case that we had not previously seen in tests with a couple of devices and are now troubleshooting this.


Asked at my MVNO if my IMEI/phone number is on some VoLTE “block list”. They said its not, my device is allowed to do VoLTE. Still I didn’t get it working on the Deutsche Telekom network. I’m now a bit lost on how I could further investigate this issue.

Maybe in the end I’ll just switch my SIM to Vodafone or Telefonica-O2.

What is the name of the tool/utility?

I would like to replace PureOS with NixOS and want to verify if the tool/utility is either available in or can be packaged for NixOS.

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This would be a very exciting project. Please write a report when you have some progress.

The utility is there in Purism repos, but for some reason purism still not bump the firmwares…

Maybe this one:
Files · main · Librem5 / bm818-tools · GitLab (puri.sm)

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But what is the name :thinking:

I do not want say anything till Purism_joao acevedo reveal all. just wait.

That is putting some pressure on me :wink:

AFIK the tool was not yet released.


I am using a SIM card from Telia, Sweden. I have not yet updated the modem firmware, but I wanted to try and see if I could enable VoLTE on my L5.

purism@pureos:~$ sudo /usr/bin/bm818-volte on
[sudo] password for purism: 
/usr/bin/bm818-volte on
enabling VoLTE

That looks alright, but when making a phone call my phone still goes from 4G to 3G or 2G, so I guess it isn’t working.
Using the /usr/bin/volte-gui tool, it shows that VoLTE is not enabled. /usr/bin/bm818-fw-check shows nothing

Modem Firmware is: [empty]

Both two gui tools, exit with /dev/ttyUSB3: Access denied although I have added purism to the dialout group.

@joao.azevedo Is it safe to upgrade the modem firmware, and if so, could I get a PM on how to do that?


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I think it used to be that you need to restart the phone (really the modem?) after enabling VoLTE. Did you do that?

Not explicitly after issuing the command, but phone has been restarted since then, so yes. Question remains though, why I am getting warning messages and the fw or the state is not picked up by the gui tools.

Yesterday I wasn’t able to make phone calls.
After entering a number and hitting the dial button, the display said “calling”, but no actual call was made.
The upper toolbar showed a 4G connection with max. signal.
Using Internet (data) worked fine.

After some research I discovered that my carrier setting was set to 4G (preferred) and 3G only.
When I changed this setting to 2G, 3G and 4G (preferred), everything worked again.
My carrier is Vodafone (NL).
I suspect that this behavior is related to VoLTE.
Can anybody confirm this?