VoLTE support progress

I am not sure whether any of the PinePhone community’s work on the EG25-G will be transferable to the BM818 in the Librem 5.

The drivers for the PLS8, BM818 and EG25-G are all 100% free, but all of them use proprietary firmware, which is stored in the modems themselves. From what I have read, the PinePhone community has had a lot of trouble with the Quectel EG25-G and Quectel doesn’t answer the community’s questions.


Quectel EG25-G is going to work(WIP)without root/firmware closed source space. Then all driver running in user space. So i think broadmobi will compatible con Quectel EG25-G maybe.

The EG25-G will still not be fully open source:


I talked last 2 week with Ondřej Jirman(Hacker Kernel Developer) he told me that it looks possible to run the entire modem in the user(gsm libs)space completely free and without the need for firmware-closed in root space. Martijn Brian may speak only at present.

That’s some good info there. Maybe it can be put in the Community Wiki. It likely won’t be frequently asked but an FAQ usually contains some IAQ. :wink:

Oddly the module in the PinePhone is global (almost all LTE bands) while the BM818 seemingly does not offer a global variant.

I added it: https://source.puri.sm/Librem5/community-wiki/-/wikis/Frequently-Asked-Questions#218-how-are-the-thales-cinteron-pls8-and-broadmobi-bm818-modems-different

The EG25-G is pretty unique. I don’t know of another company that offers another modem like it that is capable of covering the entire world.


Are you saying that THALES PLS83-W IoT module delivering global High-Speed LTE Cat.4 isn’t good enough for you? Oh well, I guess I’m misunderstanding you, for sure :joy:!

That must be a new chip. When I searched a year ago for a global LTE modem, the only one that I found was the EG25-G. I know that the EG25-G’s press release said that it supported more LTE bands than any other modem on the market when it was released in 2018.


Yes, there is high probability it is not available at this moment (Q1/2021), but with the same LGA-156 form factor (soldering mount) compatible with the Cinterion PLS8 modules. To me this looks like some kind of additional light, besides having EG25-G on board, at the end of long Linux LTE connectivity tunnel, global one, including voice support for LTE via VoLTE and CSFB for 2G and 3G. Therefore my hope here, nothing more and nothing less, that Cinterion PLS83-W might be offered once confirmed (perhaps) it can be used/put on M.2 card.


I lucky to own a L5-R5 i not using as my daily driver because i do not have a cover phone yet and i need too GTK4 in PureOS to run superfast and superfluid the system and also i am waiting for Purism to start selling cover phone protect.
But I did a test on calls to test the modem broadmobi, it worked all fine, but i see that when i do a call it changed the netwotk from 4G to 3G, i think this is a bug that recently was found in other libs and that perhaps exists in modem-manager. The first phones 4G was enable to make call under 4G but without volte, the volte features was later, I hearing some news ago that some carrier is going to block call under 4G without volte. But I am not sure of this news.
Also i checked that the Thales modem is more open than Broadmobi. @amosbatto already said that BM818 is using same chipset that EG25-G so if all that is true i stay with BM818 at the moment, i think good things will happen with BM818 in sooner time.
I will tracking the issue: 4G to 3G in calls.j


Phones w/o VoLTE on Verizon Wireless are completely useless - I gave it a shot.
As for ATT, it depends on the coverage of the home area and commute. In my case , it was close to useless, because 2G/3G signal is terrible , so most calls dropped or went to voicemail when people tried calling me.

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My assumption has been that the Librem 5 will not be allowed on the Verizon, Sprint, or U.S. Cellular networks in the U.S. because they only allow approved devices. Am I wrong on this?

My second assumption has been that the Librem 5 will therefore only be allowed on the T-Mobile and AT&T networks in the U.S. It seems I have only seen claims of functional calling with the Librem 5 on the AT&T network so far. Am I wrong on this?

Since T-Mobile is no longer allowing non-VoLTE phones on their network as of 01/2021, then my assumption is that anyone currently using or ordering a regular Librem 5 at this point with the BM818-A1 modem, will only be be able to use the phone on the AT&T network, and then only until 02/2022. At that point, AT&T has announced that they will also no longer allow non-VoLTE phones on their network.

So, it seems that unless you are currently using a Librem 5 USA with the PLS8-US modem that supports VoLTE, at this point you are therefore using a Librem 5 only on the AT&T network, and then only until 02/2022, unless Purism is able to achieve support for VoLTE on the BM818-A1 modem by then, or is able to offer the PLS8-US modem of a different VoLTE-enabled modem in the standard Librem 5. Am I wrong on any of this?

A number of people have reported full functionality on T-Mobile and AT&T. See: https://source.puri.sm/Librem5/community-wiki/-/wikis/Cellular-Providers

The question is whether T-Mobile and AT&T will start implementing whitelists in the future. T-Mobile said last year that it would start restricting its network to only phones that have VoLTE support in January 2021, but I haven’t seen any reports that this is actually happening.

I gathered most of the info on that wiki page from what people have reported on this forum, so you can ask the people who reported that info whether they have seen any restrictions from T-Mobile so far.

Since nobody in the community has done much testing on those networks, it is hard to know. Somebody in the US has to test and report their experiences. TLG reported that he couldn’t get Verizon to work. However, historically those networks had whitelists, so I assume that they won’t work with the Librem 5.


Thanks, Amos. I’ve looked at that wiki list which is really short. Actually, it only shows a single U.S.A. L5 user on Reddit who reports voice, text, and data on T-Mobile. He apparently gained access in December. That same user comfirms Ting does not support the L5 on T-Mobile because Ting requires a VoLTE-enabled device.

There are a couple challenges with that list:

  1. The reports of network access don’t specify when it was obtained. Anyone getting onto T-Mobile with an L5 yet during 2020 may not have had any trouble at the time, but we don’t know whether they are still able to place voice calls since January 1st. Having a date stamp cell in that spreadsheet to document the time of the access report would be helpful.

  2. We need more data in the list. For example, there actually isn’t anyone on it yet who reports getting onto T-Mobile during 2021. Also, we only have two MVNOs on the AT&T network reported so far that have allowed L5s, PagePlus and Red Pocket.

It seems to me that the right questions aren’t getting asked and answered about the L5, VoLTE, and network access. Here’s the questions that we all should all have answers for, from Purism or the community:

–Is AT&T now the only network that will allow L5 access for voice, text, and data? If so, then is this because AT&T is the only network that will allow both unlocked and unapproved devices, or is it because it is the last network to still allow non-VoLTE enabled devices as of 01/01/21?

–As long as AT&T allows the L5 for voice, text, and data, then will all MVNOs on the AT&T network therefore also allow the L5?

–Has anyone with a new L5 since 01/01/21 been able to access voice, text, and data on any network besides AT&T?

–Is there something about the AweSIM MVNO that would allow the L5 to access the AT&T network for voice, text, and data after 02/01/22, even if Purism is unable to enable VoLTE on the L5 before that date?

Lacking further clarifications, it still seems to me that a new L5 since 01/01/21 will now only be allowed on the AT&T network for voice, text, and data, and that this access will end after 02/01/22, even with AweSIM, unless Purism is able to enable VoLTE on the device before that date, which they are apparently working on with at least the BroadMobi BM818-A1 modem.

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Juat wanted to add to checkout here for a T-Mobile VoLTE in 2021 report (calls fall back to 3G but work still without it as does SMS):


I agree on the questions :slight_smile:

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Interesting. A report like this raises more questions than answers as it seems inconsistent with T-Mobile’s own pronouncements. It seems their dates for no longer allowing non-VoLTE phones to access their network are “soft” targets and that certain devices are at more immediate risk of being denied access than others due to esoteric firmware/software reasons. It could be that they’re doing their best to preserve customer service and bending over backwards to help everyone migrate to a device with the new standard enabled instead of just “cancelling” everyone with legacy devices so as to avoid all kinds of tears and tribulations and pissed off customers.

Still, all of us paying attention to VoLTE developments deserve some clarification from Purism. They are not out in front of communicating which networks the L5 is currently able to access as a new device on the network, and how long that access can be considered safe without firmware/software upgrades supporting VoLTE.

As far as I can tell, it’s only the AT&T network for full voice-text-data with the L5 right now, and then only for one year from now without VoLTE enabled.


Almost none of this is within Purism’s control.

On the one side, networks will set and change the various dates around device VoLTE support as they see fit. (“How long that access can be considered safe”)

On the other side, modem manufacturers will support VoLTE if and when they choose to.

I suppose it is accurate to say that right now the only available modem (BM818) does not officially support VoLTE.

However, anecdotally, the support is there and it is only the network configuration and testing (with each network in each country) that is missing. If you really know what you are doing, it may be that you can get it working today.

I think Blind Freddie can see that VoLTE is a problem that will need to be addressed, but perhaps not more urgently than getting the phone to customers who have already ordered.


I like to preserve CSFB compatibility support for 2G here in Europe, but for those (still) using 3G (WCDMA) within Asia Pacific and Latin America (adopting the APT700 band plan) regions/countries, like you @irvinewade or @BarryK, and looking forward to use VoLTE on their Librem 5 might take a look at SIM7912G-M2 (MDM9240, S2-1085D, Cat.12, M.2 card, Global) as it should be RCM approved (or will be soon).

For the rest of us (including average joe under FCC umbrella) might be that Purism is the only one to provide some update on M.2 card(s) that will be provided or not. Therefore my question here: why or why not to consider usage of THALES DIS AIS Deutschland GmbH Cinterion PLS83-W (GCF Reference: 9540) module (LTE Cat.4 with 2G/3G Fallback)?

Also, MDM9607-0 (LTE Cat.4) supports VoLTE (like within SIM7600G-H R2 module, for example) so expecting that the BM818 M.2 modem variants will do the same is not something to dismiss, but not to forget that:


For additional info, my Red Pocket (AT&T) SIM had already been activated in another phone, so all I had to do was insert it into the L5 to have full functionality. So I suppose you could say that “AT&T allowed” it; there was no approval process for the L5 specifically, though.

Almost certainly. If you pop in the appropriate SIM.

Three. As noted before, I’m now using the Truphone prepaid SIM, which runs on AT&T in the U.S. (as well as major foreign networks when traveling abroad).

Assuming T-Mobile hasn’t shut down 3G yet, his situation could change suddenly when they start refarming. In the last 2 locations I have lived (I moved over the summer), I had problems with incoming and outgoing calls with a T-Mobile reseller (which was also Red Pocket service). [Clarification: That was with my Android.] It turns out that it was because the 3G signal was weak (or possibly degraded?), even though T-mobile had not shut down 3G totally at the time. That Reddit user may actually have issues without knowing it yet. I didn’t realize it at first, until I found out people had called me and not reached me, and then when I tested by watching my phone. (I saw a drop to 3G happen, but not a peep from my phone.) And when the Reddit user happens to move around in non-3G or weak-3G areas, he could find himself without call connectivity…maybe without even realizing it.

Just a guess, but he must have attempted to check the IMEI, and it was rejected. This is no surprise, since no network will recognize this modem, most likely. It’s an unknown device to them. I wonder if he just popped in an already-activated T-Mobile SIM or actually got them to activate it for him…?

(re AT&T) In my opinion, yes.

Surely impossible. Purism would have to construct their own nationwide network, build towers, buy spectrum, etc. AweSim is an MVNO service.

Almost certainly true. With the caveat that “allow” may entail using a SIM that’s already activated in another phone, at least until the L5’s modem starts getting recognized by the carrier as compatible.

(re T-Mobile) Their public statements about the “small” number of affected customers seem to gloss over all their customers with unlocked (non-T-Mobile-branded) phones, but we’ll see.

Agreed, although I believe they’ve said they’re investigating that now.