Using the UK model in America

If I go on holiday with this phone, will it work in America? I saw something about buying the right modem for over there, but of course, just for 4 days, that’s a lot of effort :slight_smile:

Were you planning on enabling global roaming or were you getting a local (US) SIM?

Broadly speaking, the answer is that getting the wrong modem is not intended to work but it might work if the modem that you do have happens to have a right band for the network that you choose to use in the foreign country. (That in turn could depend on where you are going i.e. if you are going into less well-served areas v. staying in the biggest cities.)

Hi, I was thinking of roaming my own SIM there yeah. Its a big town I’m visiting too so should be okay on that front.

Will you be roaming with the SIM card of your UK carrier? If so, your SIM will likely default to either T-mobile or AT&T for roaming, dependent on what partner agreement is in place between your carrier and the foreign carriers.

Reminder of the available bands of the various L5 modem variants: Will my existing SIM card work? What countries and networks will be supported? – Purism

Here are T-mobile’s LTE frequencies: T-Mobile - United States - Wireless Frequency Bands and Device Compatibility
(T-mobile also still has a 2G network, but no 3G.)

And here are AT&T’s: AT&T - United States - Wireless Frequency Bands and Device Compatibility
(AT&T has no 2G or 3G, so disregard those.)

The L5’s US modem is not whitelisted by AT&T, and hasn’t been certified for VoLTE with AT&T. It has been certified for T-mobile’s VoLTE (probably because the modem was first used in automotive applications), which is why most L5 users in the US use T-mobile, or an MVNO on T-mobile’s network. I imagine the UK variant of the modem has the same limitations, but I don’t know for certain.

What this means is that you might have VoLTE calling with T-mobile, and might not have it with AT&T. In all likelihood, though, your UK carrier probably roams on T-mobile in the U.S. (The third major carrier, Verizon, doesn’t officially authorize the L5’s modem for service on its network.)

If you’re planning to buy a local US SIM upon arrival, or an international SIM, then I would choose one that uses T-mobile’s network, as you would be more likely to have VoLTE capability for calls.

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This article might be helpful: Buying a SIM Card in the United States

Tip: Check Walmart, Best Buy, supermarkets, electronics stores, Target, etc., for prepaid SIM card options, if you don’t intend to roam with your UK SIM card.

On international SIM cards: International SIM Card Comparison: Which Is Best?

(Note that eSIMs are not an option with the L5, obviously.)

Hmm, yikes, better find out who my network would roam onto then. Maybe it would be easier to get a SIM there and have a temp number for the week.

Yeah, the EU modem doesn’t align very well with T-mobile’s or AT&T’s LTE bands; the lower bands especially are needed for good coverage over longer distances between towers, and inside buildings, I believe. (I’m no expert, though.)

But even if you buy a SIM here in the US, your UK modem would still be lacking the needed bands for good coverage, unfortunately. You might have to consider using another type of phone for your trip.

I was going to also suggest an international data-only SIM as another option, but only if you don’t need calls and texts over the mobile network (i.e. if you use some chat app instead of the carrier’s communication methods). But that would also hinge on having enough of the right bands, LTE or 2G, to get on some network over here.

It’s very disappointing that there’s no L5 modem that has international coverage yet.

You can use OpenCellID . org to check density and type of coverage where you’re traveling, although it doesn’t tell you the specific bands in an area: OpenCelliD - Largest Open Database of Cell Towers & Geolocation - by Unwired Labs

Or you can check T-mobile’s and AT&T’s coverage maps.

Cellmapper might identify the specific bands.

Minor correction: The lower frequency bands especially …

There is no rhyme or reason relating band number to frequency - and hence without clarifying whether “lower” refers to band number or frequency, the statement is ambiguous.

Obviously Purism is limited by what the market for compatible, suitable, supported M.2 cellular modems provides but, yes, it would be simpler for Purism and better for a certain cohort of Librem 5 customers. (I would be very tempted to buy a global variant and do a one-off changeover if such a modem became available, just so that it’s something that I can forget about, even though that would be a relatively expensive exercise due to the shipping cost.)

Random question: Is it a practical and available option to rent a (mainstream) phone in the US for the duration of the trip?

That has some advantages and some disadvantages e.g.

  • advantages: will definitely work, and they can probably supply with a local SIM all good to go; you don’t have to worry about the fascist US authorities :slight_smile: forcing you to give them access to your device and/or seizing it as you cross the border
  • disadvantages: you don’t have any of your contacts loaded or any SMS conversations etc.; there is a certain element of trust involved in that i.e. using a “random” phone, so it wouldn’t suit all customers
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Me, too.


The only rental options of which I’m aware are those offered by the usual international-travel-SIM suspects… and I think they’re fairly expensive. (Example … and Example)

OP could, I assume, use some kind of pocket WiFi device, as depicted in the second Example, with a local prepaid SIM, but it might drain the L5’s battery faster than normal. And there’s the added expense of buying a separate device, of course.

It would be better to walk into one of our big-box stores and buy a cheapie prepaid Android with a month of service included. But if the OP already has an old Android or iPhone available (and not locked to a specific UK carrier), that, plus a local prepaid SIM or the OP’s current UK SIM would obviously be less hassle.

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(I only looked at the first link) When you say “expensive”, you mean the call costs and the data costs, right?

I mean if you didn’t have a spare mainstream phone then for 4 days the actual total rental cost for the device looks reasonable just to make the problem go away.

Taking the Samsung as an example, even at the special sale price of US$5.71 daily for week one, the first 7 days add up to $40. An additional 7 days at the special sale price of $2.50 per day adds another $17.50 to the total. (Going past the planned rental period would add $10 per day.)

The phone rental includes only $5 of airtime. After that…
rates ($200 per gigabyte/$0.49 per outgoing minute/$0.20 per outgoing SMS) and/or discount plans (much more reasonable data costs).

A prepaid Samsung+service can probably be had for as little $20 - $40 from, say, Walmart or Amazon, and will probably include some data, calls, and messages. (I’m guessing on this one. And maybe not Samsung.)

But yeah, for 4 days only, the total outlay is not that much…unless the company forces a minimum rental period, etc. There are shipping costs for the phone, though, as well.

And it looks like the minimum top-up is $25.

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If you can get on (from the UK you will have to use a VPN through a server in USA, to avoid diversion to the local Walmart site), search there for “Boost Mobile Preloaded 3mo/5GB SIM Kit”.

Boost is a MVNO using the T-Mobile network. For $14.88 plus any applicable tax, you get the SIM with 3 months of unlimited voice and text, also data of 5GB/month.

It may or may not be available at a local Walmart where you are going. The website warns that the instore price might be different from online purchase.

All warnings by Amarok and irvinewade should be noted, regarding compatibility of frequencies.


And to expand on that, the OP’s UK modem still won’t be compatible with Boost Mobile’s LTE frequency bands, though the SIM should work well in a different carrier-unlocked phone, as long as the device’s bands align with Boost Mobile’s. (Boost Mobile is an MVNO that uses either AT&T’s or T-mobile’s infrastructure… but not both; that would require two different SIM cards. Further, if the phone hasn’t received AT&T VoLTE certification, AT&T might disable calling as a “courtesy” to you. Should be fine with a T-mobile-based SIM, though.)

I also see the Boost Mobile Paygo SIM at for about $10. If OP has an alternate device available, the IMEI and/or specific model number can be checked for compatibility on Boost’s website, probably. I’m not sure if they currently let you choose whether to get a T-mobile-compatible or AT&T-compatible SIM. Might depend on the specific device or your home address… which could be a problem for a foreign visitor.

Another resource for OP: Buying a Prepaid Sim Card for the USA in 2023 -

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Yeesh, this does sound fraught. I think I’ll best best to just dig up a sh*te old Nokia phone and take that or something. I wouldn’t want to get there and can’t ring anyone.

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Check the LTE/network specs of your Nokia here: All Nokia phones

Hopefully it will match T-mobile USA more than AT&T. If it hasn’t been certified with T-mobile for VoLTE, at least it would have some 2G coverage, whereas AT&T is probably a non-starter.

I’m sure we would all benefit from hearing about your experience when your travel is over.

(You might want to try and get your most important contacts on Signal or some other chat app before you go, just in case.)