Choosing the Modem

I know the gemalto would work perfectly in the US on AT&T

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When I get my L5, I will buy the other modem variants so that I have more compatability

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Hi fralb5, which carrier in France is better with E1, and which with T1? I have an SFR SIM. I would love to be able to use a single modem. I have been assuming I will have to have a different modem when in US (A1) vs in France (E1). Thanks.

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You can compare the frequencies of the French networks from this list…

to the Purism modems’ listed frequencies here…

I would pay special attention to the LTE bands.

See here my review about it :

About default modems on each continent, a previous post: T1 Modem Variant Works in Librem 5. Details shown when the little arrow is clicked.

The default Broadmobi modems (from manufacturer’s site ):

BM818-E1 (--> Defaults: Europe)


BM818-A1 (--> Defaults: North-America)


BM818-T1 (--> Defaults: Asia, Australia, New Zealand)


The optional additional Thales (formerly Gemalto) modems (from manufacturer’s brochure and other documents on site). There hasn’t been a verification on these yet by Purism. They’d have a bit slower data but VoLTE support:

PLS8-E (--> Europe)

LTE: B1/B3/B7/B8/B20
3G: B1/B3/B8
2G: 900Mhz/1800Mhz
(Voice Support for LTE via VoLTE (Voice over LTE) and CSFB (circuit-switched fallback))
(33% lower peak transfer rate compared to Broadmobis, DL: max. 100 Mbps)

PLS8-US (--> North-America)

LTE: B2/B4/B5/B17
3G: B2/B4/B5
2G 850/900/1800/1900MHz
(Voice Support for LTE via VoLTE (Voice over LTE) and CSFB (circuit-switched fallback))
(33% lower peak transfer rate compared to Broadmobis, DL: max. 100 Mbps)

Note on South-America based on limited search: BM818 covers bands better. For instance Argentinian, Brazilian, Chilean, Paraguayan and Peruvian networks will benefit more from T1 modem as it covers all the combinations. Bolivian networks on the other hand seem to benefit mostly from A1 modem. If you want to use PLS8-modem, please check first which network you will be using and what bands it has as some operators use bands that are divided between E and A1/US models (often only B4 for LTE).

Note on Africa based on limited search: Algeria, Botswana, Egypt, Ethiopia, Niger, Nigeria, Kenya, Mozambique, Senegal, South-Africa, Tanzania, Zambia, Zimbabwe all have networks that predominantly have B1 band (some B3 and B20 here and there) as well as GSM900Mhz. Therefore the E-models should be the default.

Note on Middle-East based on limited search: Bahrain, Iraq, Israel, Jordan, Kuwait, and Saudi-Arabia (as well as Pakistan and India) may be best served with an E-model modem. Mostly B1 and B3 networks, some B5 and B8 but also B40 in couple of places.

Note on Antarctica based on limited search: No network information found. Ski near the Argentinian base to use GSM or use base wifi (satellite).

If you travel a lot, or live near borders (where you may want to use neighbouring towers), you maybe need to take that into consideration as well (use the aforementioned frequencycheck-site).


@Purism, all we travelers really need is one modem that works everywhere. :rofl:
(Pretty please…?)


I concur wholeheartedly. I currently have a dual-SIM Motorola phone which cost less than $200 that works in both the US and France (I assume the rest of Europe as well) with (I assume) a single modem.

As it is, it looks like I will need to order the BM818-A1 and E1 when I get the email, for the MVNO I use (which uses AT&T network) in the US and to use SFR in France. I can only hope it will work in the US because I used the LTE discovery app on my Motorola phone recently and it showed that it was using AT&T LTE band 5 which doesn’t seem to be supported on any of the modems listed by Purism. Hopefully I will be able to reach another AT&T band that is supported.

I agree that lack of B20 limits the usefulness of the BM818-T1 in Europe.

In the UK, the main 4G bands that you need at the moment are B1, B3 and B20.

All of the UK networks use B20, but not all of them rely on B20 to the same extent.

If you’re on the ‘O2 UK’ network (or on an MVN that uses O2’s network) and you want 4G, then you need B20. It’s their main 4G band.

‘Three’ seems to be the UK network with the least reliance on B20. Most of their coverage is B1 or B3, so you don’t need B20 in order to get a 4G signal on Three, but you might suffer from reduced coverage without it.

The BM818-T1 is probably adequate if you are just visiting the UK. It should give you good 2G or 3G coverage. It only really falls down on 4G, and that depends on which network you are connected to and where you are physically located. The BM818-T1 is certainly a better choice for visiting the UK than the BM818-A1, which has almost no compatibility whatsoever with European networks.

Another factor people might want to take into account when choosing the modem is whether or not it supports VoLTE. The PLS8 modems might not support as many bands as the BM818 modems, but they do claim to support VoLTE. (It’s in the datasheet.) The BM818 modems could potentially support VoLTE, but I cannot find information that categorically confirms or denies that,

So, yes, it is complicated.



All three BM818 modem variants appear to support LTE B5. I’m using B5 right now.

Sorry, my mistake. I must have been looking at a subset of the information instead of the full list. At this point I wonder if getting the two PLS8 modems would be a better choice, since theoretically there is VOLTE support and given I can’t find a single BM818 modem that would be likely to work for me both in the US and France.

Is your actual phone working in both US and France ?
If yes, it would be interesting to get the list of supported bands by it (can be found with the model name)
With the bands list by modem ( and the tower mapping ( you could figure out more precisely the bands you need in the regions / counties you go

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Yes, the phone works in both the US and France. At least it was working in France with my SFR SIM card as of February last year. The phone is a Moto G5S plus. The specs of the phone are here. The 4G LTE bands are B1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 25, 26, 38, 41, 66. I didn’t check with an app exactly which band(s) were being used by SFR on my phone.

Interesting, your phone doesn’t support B20 which is used at 41,3% by SFR (using also B1 (14,6%) B3 (26,7%) B7 (16,1%))

Does someone know an app indicating which band is currently used by the smartphone ? (unless it’s already availaible somewhere in android or iphone)
It could be a huge help for everyone trying to choose the modems

I used LTE Discovery.

So I have gotten the email telling me I should get the phone in the middle of March. At this point, with more and more people getting the phone I am still having trouble determining which modems are working with AT&T, as I saw someone saying it wasn’t working for them. Since the PLS8-US supposedly supports VOLTE I would prefer that one for the US. Has anyone with the phone and the PLS8-US modem successfully used it on the AT&T network using LTE?


Sorry, I had already looked at that and I looked at it again. It doesn’t seem to answer the question. Is anyone connecting to AT&T using VOLTE and if so, using which modem?


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I’m using an AT&T MVNO (i.e. reseller of AT&T service) with the BM818-A1, which does not have VoLTE capability yet. Hopefully, a software/firmware update can eventually fix that, but it’s not certain.

I’m not sure the PLS8-US is available for purchase from Purism yet, but you can email Support and ask them.