I have an HTC A9s. I could not find it on the US page of the manufacturer so I went to the UK page.

According to the specs, it does have the US frequencies:


850/900/1800/1900 MHz
3G UMTS (#UL):
850/900/1900/2100 MHz
4G LTE (#UHL):
FDD: Bands 1, 2, 3, 4, 5, 7, 8,12, 17, 28
TDD: Bands 38, 40
4G LTE (#UL):
FDD: Bands 1, 3, 7, 8, 20

Will I be able to use it in the US for calls and Internet?

  • 2
    HTC is not European company...
    – user45851
    Commented May 23, 2018 at 14:20
  • 26
    @9ilsdx9rvj0lo in this context it clearly means "For the European market"
    – Gizmo
    Commented May 23, 2018 at 14:43
  • 1
    realistically you need to use AT&T
    – Fattie
    Commented May 23, 2018 at 17:37
  • lycamobile.pl is a good "everywhere" sim these days
    – Fattie
    Commented May 23, 2018 at 17:39
  • 3
    @Fattie T-Mobile should work perfectly fine given it supports the 1900 MHz legacy GSM and UMTS network, and their primary LTE bands 4 and 12. This phone covers the same T-Mobile US bands as an iPhone 7 purchased directly from the carrier.
    – user71659
    Commented May 24, 2018 at 2:32

6 Answers 6


Many years ago, it was highly unlikely that a European cell / mobile phone would work in the US.

More recently, but still quite long ago, your phone might work if it supported the US bands.

In both cases, the answer might have varied from state to state or city to city.

These days, you are unlikely to experience a problem. Phones are now much more standardised than in the early days. I have not experienced a problem roaming in the US for a long time.

To be absolutely sure you would need to check with your current service provider and research ones in your destination area.

I suggest that you check roaming charges carefully: they might be very high, especially for data. You might want consider getting a local SIM card. How easy this is seems to vary a lot.

  • 2
    My situation is the reverse: I'm a US citizen who travels to the UK, but this answer exactly matches my experience. Getting a UK SIM card for my US GSM phone has worked for me without issue. Getting a local SIM card also makes it easier for everyone else to get a hold of me, secure in knowing they won't be charged exorbitant long-distance fees.
    – tvanc
    Commented May 23, 2018 at 14:19
  • @turibe Yes, things are much easier in both directions these days. I would expect my answer to work both ways. The issue that is more complex is acquiring a local SIM card. The ease of this varies a lot from place to place.
    – badjohn
    Commented May 23, 2018 at 14:37
  • 1
    @turibe The exception is if the people calling you are in your country of origin instead of at your destination, in which case getting a local SIM at your destination will make the call international for them instead of local. :)
    – reirab
    Commented May 23, 2018 at 21:54
  • @reirab: so you get a dual-SIM GSM phone and have both a US and local SIM. These are common. Btw T-Mobile postpaid allows cheap international roaming and free international texts.
    – smci
    Commented May 24, 2018 at 4:29
  • 1
    @smci Yeah, I know you can get dual-SIM, but at least the last time I was in the market for a phone, most U.S. smartphones weren't dual-SIM, even the high-end ones. I haven't looked at what's out there in a while, though, so perhaps it's more common now.
    – reirab
    Commented May 24, 2018 at 5:21

In addition to the other answers:

  1. Check the roaming charges for your provider/subscription. They can be extraordinarily high. The biggest issue is data, as your phone can use a lot of data without you even noticing or even doing anything actively on your phone (background updates of apps, e-mail...).

    Providers often given data rates using units such as MB or even KB. 0.10 €/MB doesn't seem much, but when you use a few hundred MB per day, that easily adds up to hundreds. Some others will include calls and data for some destinations, but there may be a cap, or a threshold beyond which they start charging per MB.

  2. If you decide you definitely want to be able to use voice & data while in the US:

    • check that international roaming is enabled with your mobile provider. Some enable it by default, some don't. Some may require a deposit or something similar to enable it. It may vary depending on your contract.
    • check for any relevant "add-ons" which may reduce your costs.
    • check that your phone has roaming and/or data roaming enabled (the two settings may be in different places).
    • monitor your usage.
  • Can only agree on the cost checking for data. I know of roaming data bills for 15000$ for 'checking facebook'.
    – Aganju
    Commented May 23, 2018 at 14:15
  • The UK Three network has "feel at home" for many of its contracts which allows you to use your phone in many countries without any roaming charges. This includes the USA. This roaming use includes calls, texts and data but not using the phone as a WiFi hotspot.
    – uɐɪ
    Commented May 23, 2018 at 15:07
  • @anomuse That's still less than what my Finnish operator charges for roaming data in the US (12,49 €/MB). Fortunately there is a cap, cutting the data once a threshold is reached, but that means just a couple of MB. Commented May 23, 2018 at 19:52

This is an excellent site I'd visited to figure out which SIM cards would work on my parents' Mi A1 phones in Canada - https://willmyphonework.net/.

If you are looking for roaming, it might be expensive. You are probably better off getting a US SIM (T-Mo, Ultra Mobile etc.) and using it for the duration of your stay. Your choice, of course, but just a suggestion.


yes your phone will work also in the US. Regarding internet: you should have the option for data roaming active, otherwise it will not connect to the data network.


Yes, GSM phones will work in the US, either on GSM carriers (at&t, T-Mobile) or their resellers (MetroPCS etc.) or MVNOs (Virgin Mobile, LycaMobile etc.)

To solve the dilemma of international roaming for call/text/data, get a dual-SIM GSM phone and install both a US and local SIM. These are common (OnePlus, Samsung, Huawei, Xiaomi, Honor etc.) Obviously, when you're in Europe, turn off data roaming on your US SIM (and restrict or disable bandwidth-hungry apps), and vice versa.

Btw T-Mobile postpaid allows cheap international roaming and free international texts in most foreign countries. As long as the T-Mobile postpaid account has been active domestically in the US for the preceding n [*] months, and the foreign usage does not exceed fraud threshold. [*] T-Mobile reps have quoted me numbers anything between 1-6 months.


Not all European GSM phones work in the US (regardless of the SIM card). In fact I tried to use one of my GSM flip phones (bought new in 2015) in New York and it just said "no network", it didn't even have the possibility for emergency calls.

Part of the relevant information is here on wikipedia: https://en.wikipedia.org/wiki/GSM_frequency_bands

Europe uses GSM 900 and 1800 ("dual band").

America (not only the US. Also Canada, South America, Central America) mostly uses GSM 850 and GSM 1900.

Smart phones are typically quad band phones. I assume the manufacturers don't want to bother with different models for different parts of the world, or nowadays, the possibility to use your smart phone everywhere is far more important than with "cheap" phones that could only text and phone - after all for these services you also need a decently priced plan, or might just be unavailable (time zone difference, vacation, …) or get a throw-away phone in the country you're visiting.

You already collected the relevant information about what GSM standards your phone can do, and in fact all relevant ones are covered.

  • This is true but no longer very relevant. 2G GSM service may in fact be gone in the US (here's AT&T's announcement of their shutdown) while most Canadian carriers never had a 2G GSM service to start with. 3G UMTS service is now quite ubiquitous but is used on a somewhat different set of bands than you list. Most people interested in data roaming would prefer 4G LTE service anyway because it is faster.
    – user38879
    Commented May 26, 2018 at 20:58

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