VoLTE support progress

This is the sort of :poop: that makes me lose my noodle.
Not my area, but is there any possibility of being able spoof ATT/Verizon as to the identity of one’s L5, given that we can (hypothetically) do what we want on it? That is, what technology is used by the whitelist, and can it be corrupted?


Just one more or less minor addition to that - we (as in Purism) currently have no plans to get additional carrier approvals. Getting carrier approvals is a PITA and in most cases bound to very high restrictions on the device and a very expensive qualification process.

I don’t think this represents current policy at Purism. Since that time, Purism announced its AweSIM program, which makes Purism an MVNO of both the T-Mobile and AT&T networks. That means that Purism will have to eventually get the L5 on the whitelists for those two companies, so it will have to get the BM818’s VoLTE to be certified to work on their networks.


That’s encouraging info. Thx again Amos!

Would the modem then fallback to 2G/GSM?

1 Like

Yes, that is how it works. If 4G isn’t available, then it falls back to 3G, and if 3G isn’t available then it falls back to 2G. Most people are able to get 4G data, but because they don’t have VoLTE, they can only make phone calls with 3G or 2G.

I think the way the US carriers have implemented VoLTE with whitelists is ridiculous, and frankly the US government needs to step in and properly regulate the industry to stop carriers from excluding phone models that support VoLTE. The US mobile industry has all kinds of anti-consumer practices that a functioning government shouldn’t allow, but lobbying power and legalized bribery in the political system allow this to happen.


I have bad news. L5 doesn’t work like that.
Vodafone here decommissioned his 3G network, so only 4G and 2G are available. If I set the network mode to “2G 3G 4G (preferred)”, that’s the default setting, I cannot get incoming calls, sometimes it also fails to make calls. In order to be able to use the L5 like a phone I have to set the network mode to 2G only … and, of course, data connection becomes a pain in the neck.
I guess the phone is taking too long to switch from 4G to 2G when receiving a call so it goes to voicemail everytime. If it is set to 2G only it rings perfectly.
I’m in contact with Purism support in order to try and fix the issue, but it doesn’t look easy.


Wait, isn’t the problem that they’re excluding phones that DON’T support VoLTE after Feb 2022?
Or is that a separate problem, and you are you saying that they’re excluding phones that have the technical capabilities, but are arbitrarily excluding some for purposes of their own? Both are shady practices

AT&T already shut down their 2G network in 2017. T-mobile is shutting theirs down in December 2022: https://1ot.mobi/resources/blog/a-complete-overview-of-2g-3g-sunsets

That’s what @amosbatto was referring to. However, as I understand it, there’s an entire certification & testing process that OEMs must go through with the networks to get their devices qualified. There may also be concerns of interoperability across various networks, especially internationally, and different implementations of IMS. So it’s probably not as simple as “Device A has the ability to make Voice over LTE calls, so it should work with this carrier.”



1 Like

Well, someone said earlier that the EU doesn’t have the whitelist thing so maybe the Librem5 will end up only being feasible as a phone in Europe and perhaps other places outside of the US.

I am not tied to a particular MVNO in the US, but I prefer an MVNO on top of the AT&T network as it was the only one for which I could get a strong enough signal at home (also where I used to work). It is a pain to switch to another network just to find out that it doesn’t work at home or somewhere else (like work) where you spend a lot of time, but one might have to consider it if only some of the US networks support Librem5.

Of course, most newer Android and Apple phones support WiFi-calling which can be used to work around weak signal strength (a relative of mine now uses WiFi-calling to get around this issue), but I guess this is something the Librem5 doesn’t have either. Anyone know if there are any plans to support that? I don’t know if that would be a change to the Calls app or if it would be done somewhere lower in the stack.

In Europe, more specifically in the EU European Union, the situation is that: as long as a device complies with the regulations/standards, the carriers have to accept it in their network.


Interesting. Is the issue that the BM818 modem is unable to downgrade from LTE data to GSM when you receive a phone call or that it takes too long to make the switch, and the caller hangs up? With the PinePhone’s modem, it was taking too long to respond to calls and people were losing calls, but the community is working on improving the driver so it is much faster now.

Yes, but the issue is that the US carriers are making it much more difficult to use their VoLTE than the carriers in other parts of the world, because they have a limited number of phone models that they have included in their whitelists.

I’ve had the same issue. It seems to be that it takes too long to switch to 2g and the call goes to voicemail, as it’s usually fine if already on 2g.

There is part of me that wonders if it’s partly spending time looking for 3g. However there is no setting to only use 2g or 4g.

Agreed, and the carriers should be forced to accept any compatible device.

AT&T and Verizon do have whitelists, while T-mobile technically doesn’t; they are fairly open to any device as long as it has been tested and certified for their network. I suppose you could also call that “whitelisting,” in the same way as FCC or EC certification “whitelists” electronic devices for market.

At any rate, that is just how I understand it as an unqualified layman who has done some reading on the internet. :wink:

I don’t think so, I set manually the network mode to 2G-4G but it behaves the same
mmcli -m 0 --set-allowed-modes='2g|4g' --set-preferred-mode='4g'
(note: check the modem number with mmcli -L and adjust the command accordingly)


Nope, the caller doesn’t hang up, the call goes to voicemail … I don’t know exactly what is the issue, I guess it takes too long to make the switch, but I’m not 100% sure it’s able to downgrade automatically to 2G. I wouldn’t know how to find out.

For a data-only SIM solution that bypasses local carrier device restrictions, I suppose that an international travel SIM might work, although most of them are expensive to use.

I did find this one, though: Surfroam, HQ’ed in Estonia, which has a data-only travel SIM that seems quite reasonable for many countries (including €0.01 per megabyte in Europe, €0.02 in the U.S and Australia). That’s not too bad, especially for low data usage. And it can be kept active indefinitely by recharging at least every 365 days.

In any case, sounds great for actual travel abroad. :slight_smile:

[Edit: I just ordered a Surfroam SIM, so I’ll test it and report on how well it works (in the U.S., since I’m not traveling overseas any time soon.]


ICYMI: Using Phones with No-SIM Cards and Other Privacy Experiments

While waiting for the Librem 5 USA, I purchased one of Braxman’s De-Googled Pixel 4a phones running LineageOS 18.1 which has been working great except for SMS via ting.com on T-Mobile so I’m seriously considering a non-SIM card option as described above or abandoning SMS altogether.

1 Like

I have 3 deGoogled Pixels( 2 with Graphene and 1 with Lineage. They both work very well on AT&T


My data-only Surfroam SIM arrived from Estonia (to California) in just 4 days. I initially had no success getting it to register with AT&T. The Surfroam team helped me over chat and I eventually got a strong LTE signal. This is on an Android phone.

I successfully added a SIP account to the Android with Linphone as the client (native Android dialing client probably works, too), as an extension of my home VOIP phone, and it works well. I can set it to either ring both my home phone and the Android simultaneously, or let my home phone ring a few times, then ring the SIP extension.

You could also get a VOIP provider for a dedicated mobile account only (with no need for a home VOIP phone), I’m sure. Some providers even have some basic SMS functionality.

So, I think that with a data-only SIM and a SIP account, this type of setup would allow anyone to use the L5 without VoLTE as an interim solution, once SIP functionality is added to the dialer.

P.S. Surfroam works in most countries, and the cost per MB is fairly reasonable, compared to other travel SIMs.

EDIT: These tricks might be useful, too: https://20somethingfinance.com/how-to-send-text-messages-sms-via-email-for-free/


Fortunately, SIP calling is coming: