VoLTE support progress

I don’t know how sceptic providers are on new modems, but I guess it is in their interest to move customers from circuit switched telephony to package switched. I think VoLTE is more efficient. VoLTE seems to be implemented differently so there may be incompatibilities between providers and calls may fallback to circuit switched calls again. Also the L5’s modems might work with some providers and not with others.

I am not an expert, but that’s what my base knowledge and Wikipedia let me believe. I am optimistic for VoLTE in Germany. :slight_smile:

pic or it never happened :stuck_out_tongue:


Has anyone tried with a modem that is certified by US carriers? I picked up an EM06-A for 35 bucks for testing once I get my librem. I realize there will most likely be other issues with a non purism modem but I wanted to try it regardless.

To make sure I understand … are we say that this particular German carrier is not picky (not checking the IMEI or modem model etc.) and VoLTE with that carrier worked without hassling the carrier? (It does of course require changes on the phone itself in order to enable VoLTE, although I assume that eventually VoLTE will be enabled out-of-the-box.)

Is it possible that the VoLTE config data in the modem is incorrect (or out of date) for the particular US carrier that you are using? (but correct for the German carrier that was tested)

I’m no expert either. So just wondering.


It required to activate VoLTE in the modem using AT commands. It does not require changes in the Operating System itself.

I also tried this, also with the E1 (European) variant of the modem, and it also worked with my German carrier, which is different from @spaetz I was also able to make and receive calls via 4G.

However like posted above, other carriers are more “complicated” with enabling VoLTE, and if your carrier requires to whitelists the IMEI then enabling VoLTE in the modem while the IMEI is not whitelisted can make calls not work properly.


It’s certainly possible. If so the config data would just be incorrect in some way that only affected outgoing calls. It’s difficult to say until we rule out carrier interference.


Just as another data point, I just successfully placed an outgoing VoLTE call to my Google Fi voicemail number. It connected and I was able to test my voicemail. Due to how Fi’s network works, it was using T-Mobile’s network in this case. However when I tried to follow up with a call to a different number, it was dropped before it could connect.

Further confirmation that the hardware supports it, but there is either a configuration change needed on the carrier end to allow it, or possibly a configuration change on the modem side, however if it’s the latter, I am curious why a call to Google Fi voicemail worked. One would think that if the modem needed changes then all outbound calls over T-Mobile’s network would fail.



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Heh, yeah it’s a throwback to when I worked at a few startups that required full Google Apps anyway, so given what I knew about carriers and privacy to that point I figured I was already compromised as long as I had an Android phone.

It’s only now with the Librem 5 that I actually believe I have a chance to live a completely Google-free life. Once we support porting an existing phone number over to AweSIM, I’ll probably be the first guinea pig :slight_smile:


I disable or block everything Google I come across… At least I hope so.
(And Facebook stuff, too. Obviously.)
But that’s a bit off-topic here, of course.

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Do you really? DeCloudus has identified almost 10,000 (yes, 10K!) google sites that potentially suck data from you…


Just an FYI. I had an AweSIM shipped with my L5 to ensure the phone met all my needs before moving my old phone’s SIM. Once I confirmed the L5 could do voice & text, I cancelled my AweSIM service. For a couple small reasons, I haven’t yet transferred my old SIM card, and my AweSIM is still in my L5. Though that latter account is inactive, this morning Chatty told me I had a new text:

AT&T Free Msg: ALERT! AT&T is taking steps to shut down the 3G network, so you can do all the things you love only faster. This means your phone won’t work once 3G goes away by February 2022 and you’ll need to change it. Starting April 12, 2021, we may redirect your call to customer service to help you upgrade your phone. Some features like voicemail won’t work during this time. To learn more or upgrade now, visit your AT&T store.


So no phone calls unless you upgrade. They might as well just say that.

It’s no upgrade — AT&T is THE WORST. I’m not even sure I could stomach an AT&T MVNO.

Unless it’s an MVNO that AT&T actually owns (Cricket), you won’t even be aware of any relationship with AT&T, except for network coverage (which is usually very good). Some of your dollars will be trickling back to AT&T, however, which is unfortunate, but at least you’re getting (a lot) more for your money.


I am supposed to get my Evergreen in the next week or so. I have gotten the shipping notice. My SIM card is for one of the MVNOs on one of the major 3 US networks. I would like to try experiment with the AT command to enable VOLTE to see if I can make and receive VOLTE calls. I am sorry if this is stated somewhere, but I haven’t found:

  1. What are the commands to enable and disable VOLTE on the BM818 A1 modem? Is there a list of all AT commands for the BM818 modem?
  2. How does one know whether VOLTE is being used or not? Is it evident by the indicators at the top of the phone? My Moto phone has an LTE indicator. I don’t know if this being on during a call means I am using VOLTE or not.


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If “LTE” disappears when you are on a call, then you are not using VoLTE.

In your network/mobile settings do you see an option to “Enable VoLTE” or “Enable Voice over LTE”? (With AT&T it is called “HD Voice.”)

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I don’t have the phone yet. Hopefully this week. However, earlier in this thread you will notice Kyle Rankin and others mentioning using an AT command to enable VOLTE, so my assumption is that this is the way you have to do it on the phone currently.

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If only!

I’m pretty sure that the answer to this is ‘no’.

If VoLTE is not being used then the phone has to drop down from LTE (4G) to 3G in order to conduct the call - and you will see this in the indicators at the top of the phone.

Assuming that 4G was available at all. If 4G is not available at all in your current location then by definition a call is not using VoLTE. Fairly obviously a pre-requisite for phasing out 3G and doing calls only via VoLTE is that 4G is available ubiquitously, so there should be no such locations by the time that VoLTE really is mandatory.

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OK, I will try again. There are multiple people on this thread who have stated that:

  1. They have used AT command(s) to enable VOLTE on the phone, and

  2. They were able to see whether it was VOLTE or not

So I am asking if one of those people could tell what command(s) they used to enable VOLTE and what they were using to determine if it was using VOLTE or not (i.e. the top of the phone display or some status command or something like that in the terminal). I am supposedly going to receive my phone this week and trying calls with VOLTE is one of the things I want to try soon after I get it.

I am not afraid to use the command line as I have been using Linux for over twenty years.