Using your GSM phone in the USA

Using your Phone in the USA. (Revised December 2013)This article is aimed at people from other countries, primarily the UK, who are wanting to save money on data costs abroad. As time progresses, there are less and less technical nuances to understand, which means that more and more people should be able to do this.

There are a number of assumptions taken into account, and they are the following

  • You have an phone which is factory unlocked or unlocked by your operator.
  • You can check your phone model on to make sure it is compatible with the mobile phone frequencies used in the USA
  • You want to know how to go about getting data in the USA for less money than your roaming rates.

Geeky Stuff

Firstly, lets tackle the frequencies thing.
There are 2 main GSM operators in the USA. AT&T and T-Mobile.

Both offer 3G and both use different frequencies.

AT&T – 850 MHz / 1900 MHz

T-Mobile – 1700 MHz Upload / 2100 MHz Download & 1900 MHz in certain areas.

Here are some popular phones and the supported frequencies.

  • iPhone 4, 4S and 5 supports 850 / 900 / 1900 / 2100 MHz.
  • iPhone 5S and 5C supports 850 / 900 / 1900 / 2100 MHz.
  • Samsung Galaxy S III (I9300) supports 850 / 900 / 1900 / 2100 MHz.
  • Samsung Galaxy S IV supports 850 / 900 / 1900 / 2100
  • HTC One supports 850 / 900 / 1900 / 2100

Quite a standard list here, nothing out of the ordinary. Maybe in your part of the world, it may be slightly different though. GSM Arena has al this information.

Ensure when you’re travelling to the USA, your support the frequencies above. Now it gets even more complex with LTE support, which is the 4th Generation of Mobile Technology, but at the moment, most people are still utilising 3G, so I wont’ go into details on 4G.

So, you’ve got a compatible phone, it is unlocked by your network or you bought it that way, now how to get cheap calls and data. There are a number of options to think about, so here are they are. There are good and bad things about each option.

UK Roaming – Three UK


So, the cheapest way to get UK calls and data, is to get a PAYG SIM from Three UK. This UK based mobile network allow you to roam to the USA and a number of other countries, and feel at home. This means calls to UK landlines, mobiles, and data comes out of your normal bundle. Therefore for £15 you have, All-you-can-eat data, 300 minutes, 3000 texts. The downside to this, local US calls are charged as normal UK – US Calls, and will come out of any other PAYG credit you have. All in all, it’s not a bad deal.


If you are already a Three UK customer, with a contract or PAYG, you’ll get this, unless you’re in the first 30 days of your contract as they don’t allow roaming. If you’re switching networks to get this on your contract phone, then make sure you time it right. Once the 30 days is up, you need to call to activate roaming.

US Networks


Wow, how much shorter this section is. This used to be so complicated, and now, they finally support iPhone on their network, and also, they offer pre-paid bundles, but each time they do something, it gets worse and worse.

  • $25 plan & $5 Data Pack for 50Mb, 250 minutes and unlimited texts. Total $30
  • $40 plan includes 200mb data, 500 minutes, and unlimited texts.
  • $50 plan includes no data, wifi only and unlimited calls and texts.
  • $60 plan includes 2GB data, unlimited calls and data.

You can spend $5 on any of these plans to get 250 minutes of calls back to the UK or Australia amongst many other countries. Also, if your phone is compatible with their LTE network, you do get the benefit of using that.

One final point to note, that if you’re wishing to use this SIM again, and not go through the rigmarole of  activating SIMs and getting credit onto them, then you need to ensure you change your plan to the basic 10¢ per minute plan. The only way you can do this is via the AT&T Customer Support Number. I tried numerous times to do this via the automated service, but eventually had to speak to someone, and it was sorted. My SIM is ready and waiting for me next time.

If you don’t want to use the SIM again, and it has $0 credit on it, you can do nothing, apart from cut up the SIM and bin it. I say cut up, because someone may attempt to use it, and you don’t want that.


I used to be with T-Mobile in the USA, and actually might go back to them. So, they have very complex plans, so I’ve picked out ones I think that will work well for people who are going on holiday.

Pay By The Day Plan is $3 a day, and gives you unlimited talk, text, and up to 200MB data at their fastest speed (they call it 4G on their website, but to me, it’s 3G still, as it isn’t running on their LTE network).

Monthly Plans – Much like AT&T here…

  • $50 Unlimited talk and text, 500MB Data
  • $60 Unlimited talk and text, 2.5GB Data.
  • $70 Unlimited talk, text and data.

All three of these plans just pip AT&T on the data allowances, but their coverage on compatible networks is much more limited. If you’re staying in major cities, you’ll be fine. Check here. 

$10 in this instance if you want calling back to the UK or Australia amongst many other countries.

Not sure on the SIM expiration at the moment, can’t see that info on their website (must be hidden).

Straight Talk SIM

Straight Talk are a Mobile Virtual Network Operator who use the AT&T and T-Mobile signals. Most of what I’ve said above will apply, so lets get into the detail on what they offer, and how much it costs.

Firstly, it is as simple as $45 per month for “Unlimited” Calls, Text and Data. I put “Unlimited” in quotes like that because their terms do not allow streaming of audio or video programming. It’s not unlimited then is it?!

Now the way it works is that you must choose what kind of phone you have to what sim card they give you. Confused? Yeah, me too. Basically, they’re 2 networks under one marketing banner. If you have a T-Mobile compatible phone, you’ll run on their network, if you have an AT&T Compatible phone, you’ll run under their network.

Sim Cards online are $14.99. Their $30 plan isn’t worth it for data, however their $45 is OK. The reason I’m giving it only an OK, and not a good, is that it costs $15 for the sim, making it $60 in total, and then you can’t reuse the sim as it will get cut off. For some it will work. For regular visitors to the USA, you’ll get a new phone number each time probably!

H2O Wireless

This uses AT&Ts network, and again there are many plans an options. There are per the minute options that can have data charged per MB, which probably isn’t the best, and the monthly plans,

  • $30 Unlimited talk and text and MMS, 500MB Data, $5 of international call credit
  • $40 Unlimited talk and text, 1GB Data, $20 of international call credit, and 100 international text.
  • $50 Unlimited talk and text, 2GB data, unlimited talk to UK and Australia landlines (and 48 other countries), unlimited international text.
  • $60 Unlimited talk, text, data, $20 of international call credit and 200 international text.

So, plenty to choose from and maybe one of the better options if you need to keep in touch with home while you’re away. Again, there isn’t a way to keep the SIM alive after the month stops, so you have to get a new SIM each time.

UK Virtual Network

Now, I don’t know what actually to call this, but spotted it on one of the recent posts on TripAdvisor. Looks to be a very very simple way, may be a little more expensive than using a US network, but infinitely simpler.


New on the block, and UK based, Telaway unlimited US, UK calling, data, and you can “keep your UK number”. This sounds excellent, and I’ve done some reading up on how it all works.

Firstly, they will supply you a new SIM card, and a new UK number as well as a US Number. You then forward your calls to this number, and people can still call you in the USA. Calls forward from your own phone will come out of bundles, PAYG credit, or per minute depending on your deal or network. Texts will not be forwarded.

So, options and costs.

  • 10 day trips are £39.99
  • 30 day trips are £59.99.

Everything is unlimited, so that’s easy, data, text, calls to USA and UK Landlines. Calls to UK Mobiles can be added and will be a per minute fee, but there is no information on that. But, just grab Skype, or use Facetime Audio to make calls to mobile phones in the UK, as data is unlimited. Longer trips you can add on more days.

Their website doesn’t go into any technical detail around which network they’re using out in the USA, and I can’t find that info anywhere else on the internet. Their FAQ is aimed at travellers, and is just a good plug and play option based in the UK. This may be easier than getting a US based SIM.


So, there are many options, and hopefully this 28th revision of this page gives people plenty of info, until someone changes their plans again. If anyone from Australia wants to get in touch if they know a company like telaway in their country, I’ll be more than willing to feature it to help you out too!

Please bear in mind that I accept no responsibility for lost money, broken sim cards, non working phones while abroad, nor do I offer any other technical support apart from this post on my web page.

Have a great holiday!

    • BlueSkyHeart

      Thank you for the valuable guide!

      As for those who cannot order the microSIM online (perhaps departing tomorrow and cannot wait for shipping :) ) you can still get it once you arrive to the States. Make sure to have the Custom APN file emailed and downloaded on your phone before you leave so that you can install it when you get the card.

      When I went into the store the clerk was very negative about using pre-paid SIM in an iPhone. Mentioned something about iPhone compressing the data differently and that therefore it is not compatible with their pre-paid network. Resist the temptation to burst into laughter and politely insist that you are willing to take the risk and splurge $15 to get the SIM (that $15 can be used to add features and talk-time, so the SIM is effectively free). After playing hardball for a little while longer the clerk got out the GoPhone microSIM, activated the data package on it, I slip it inside my phone, install the profile and the thing works!

      Depending on the state, you will also need to pay sales tax on any amount you add to your card in store, so for any subsequent refills it’s best to use the method you mention.

    • William

      Just a quick question. How do you pay for the data? is it that I buy a $50 top up card from a shop or Pinzoo take out the $25 plan then ring up att and get them to convert the last $25 from my top up into data?

      If you add the data via the att website surely it will ask you for you to pay via a credit/debit card billed to american address. I’m just a bit confused about the data bit

    • ChloeAnne_x

      I have read that we will need to use an IMEI number from an actual GoPhone when activating the sim card. Is this true?

    • Doug Lange

      Hi travelling from Australia to the States for 2 months and wanting to get a SIM card for my iPhone 6 for data and calls. I’ll be driving from Chicago to New Orleans and want to use google maps to navigate. What would be your recommendation?
      Do I buy a sim card in Australia eg telaway or wait until I get to Chicago?