3G/4G modems - Alternatives?


I am not sure about all the questions, but let’s see:

  • the SIM card slot will be integrated onto the main board and the SIM card as well as the microSD card will sit on a tray
  • I am not sure what you mean with high/low voltage SIM card detection?
  • we do not use any PCIe interface to the modem. The M.2 socket for the modem will not have PCIe signals routed to it. The modem control and data will run over USB interface, the audio data will be routed over the PCM interface of the card. We also expect that VoLTE audio data will be routed through the PCM interface, but this is still t.b.d.

Hope this helps.


Update on Librem 5 hardware?

Sorry. Voltage was the incorrect term.

Polarity of SIM_DETECT.

Fibocom, Sierra, Huawei, and Telit HIGH if SIM inserted.
SIMCom and Gemalto LOW if SIM inserted.

Will it matter if we are using Modem with the opposite polarity?

Will it be USB 2.0 or USB 3.0?


For other testing purposes, there is now possibility to order some M.2 modules over Techship AB, Sweden, but please note that they only accept registered companies and that customer registration is required to view some specified pages and for downloading software/firmware. With B28 support they offer: Fibocom L850-GL-10 LTE CAT-9 M.2, Fibocom L860-GL-10-00 LTE CAT-16 M.2, Sierra Wireless EM7430 LTE Cat 6, Sierra Wireless EM7565, CAT-12, M.2 CBRS Enabled, Sierra Wireless EM7565 LTE CAT-12, Telit LN941 LTE CAT-6, M.2, Telit LN940 A9 LTE CAT-9 M.2 and Telit LN940 A11 LTE CAT-11 M.2. This is just to show M.2 modem (future) availability yet not necessary Librem 5 compatibility (besides Linux support) and it looks like that standard size for M.2 connector is 42x30x2.3 mm or M.2 3042 (if this fits). And as mentioned within the above link: Voice Call Support: No, only Digital PCM signal input/output in socket is there. Time-Divide-Duplex (TDD) is supported as well. Here is link to Telit Connectivity Technical Support for Other regions. Anyway, without Gemalto (now part of the Thales Group) support for 3GPP Band 28 it will be (maybe) difficult to find some adequate modem card replacement.


Gemalto mPLAS9-W (here with mini PCI express connector) is hopefully something to look forward with its 3GPP Band 28A/B compatibility. Band 28A has 703-718MHz, and Band 28B has 718-748MHz UL, while Band 28A has 758-773MHz and Band 28B 773-803MHz DL. I hope Gemalto PLAS9-W with M.2 (NGFF) connector pinout will be a good solution for this topic (as well) and that there is still time (maybe) to pay (please) additional replacement (upgrade) cost for it (at least for some of us).


Have a look at this link. See what may be of interest. I am more than happy to contact suppliers.

3G/4G Module

Some inside information… Sub $150 AUD for under cat 12 is very possible.


With Gemalto now being part of the Thales group I’d be very hesitant in putting it in my device. Any company that ingrained with defense contracting is very far away from the privacy and security the Librem 5 is aimed at.


The bands look much more promising. I note though that the module is 2mm wider and 0.6mm thicker. So someone at Purism would need to comment on whether that will still fit.

Unclear whether it offers VoLTE support.

Unknown whether it is compatible with the mPLS8 in other ways for a straightforward replacement.

OK but that (mPLS8) is what is going to be in the phone unless a suitable replacement is found.


I have a USB SIM card reader that’s not doing anything. Maybe I can connect a second SIM externally via the USB port. LOL.

Seriously though I will be more than happy with just one SIM card if the phone works at all.


It is still lacking quite a few bands to be considered global.

This is a mini PCIe card. From the details given the modem wouldn’t fit on an M.2 card.

I can’t find a mention of it handling any sort of voice calling. As much as voice calls would be good VoLTE is a must in Australia. When they start shutting down the 3g network, rumoured from next year, VoLTE will no our only option.


As stated, both modem cards implement Audio 3GPP Release 8 and most of the VoLTE interface requirements came from 3GPP Release 8. And, this is just an orientation info and not helping much without direct answering if Gemalto PLPS9-W offers needed VoLTE support.
Moreover, I am finding this Telit White Paper about LTE Evolution Standardization Deployment useful to read.


I may have been looking at the wrong specs. The PDF I looked at contained no mention of whether the modules are mini PCIe or M.2. The keying looks like mini PCIe (for both the mPLS8 and the mPLS9). So probably the wrong PDF.


Gemalto Cinterion® PLAS9-W wireless module is having support for B28 and probably no VoLTE (if eventually M.2 connector model exists is also unknown). Yet recently certified Gemalto Cinterion® PLPS9-W should support both B28 and VoLTE, but I am not having any further (production) info either. Like I said, it is just something to look for.


As an interested Aussie here who is just looking for a reason to buy a Librem, a huge thank you for all of your efforts. I feel confident that there will be a solution. But, seriously. Thank you for the time you’re all putting in.


My searching has been hitting a wall. I’ve been able to find modems that support voice and VoLTE. The problem seems to be when they are implemented. M.2 doesn’t appear to be a popular choice and when a modem is implemented on an M.2 card the voice call abilities are disabled.

Outside of Quectel and Telit I haven’t had any luck in finding M.2 with voice and VoLTE.

I will continue to look and update the thread as I go.


Was there any reason that the Quectel was not appropriate / not going to work? e.g. EM06-E.

At this point we only need one working module.


The Quectel modules are perfectly acceptable. I’m just trying to have as many options as possible. Also trying to find a global unit that can make bulk ordering easier.


As long as Purism is not on the offensive side we may understand this as they need to have particular
logistics (backup) support (or vice versa). And at the end if we gain some kind of protection and if this project makes for us healthier environment, there is noting to complain. Someone will praise or judge Purism moral and ethical side one day (as positive hopefully) but (at the moment) we just want to get the best usable product based on open source Linux, our smallest but best artificial companion.


Do not get me wrong. I have great praise for Purism and the work they do.

While Gemalto was not part of the Thales Group I had less concern.

I do not believe Gemalto would have any ill will towards Purism and the community they have built around them knowing what Purisms intentions are.

The Thales Group is a different matter and what they tell Gemalto to do to the firmware is beyond our control. We may end up being unintentional victims of of their actions against others.


Does anyone have a link to details on the Gemalto PLS8 M.2 modules? No matter how much I search I can not find any reference to the existence of these modules outside of Purism.


Datasheet good enough?

What actually is the supposed threat model here? Purism treats that thing like the least trustworthy thing anyway, with no audio connected when not in a call, no memory access etc.
So, what evil thing would you put in the firmware that would actually make a difference?