Guide to International Cell Phones

Most of us have gotten used to having a phone with us where ever we go, and having a working phone when traveling abroad can allow loved ones to contact us in an emergency or simply provide a way for us to call a cab or meet up with a new friend. Here’s a rundown of the things you need to know when it comes to jumping from country to country with your mobile phone.

Geek Talk: GSM

The service standard offered in almost every country in the world is known as GSM, which stands for Global System for Mobile communications. Some people have the belief that GSM phones have something to do with satellites, but this is incorrect and probably a confusion with GPS. GSM phones are not satellite phones, which are what you should be looking for if you want a truly global phone that works even in the middle of the ocean (though they’re expensive and only work outdoors). In the United States, the major GSM service providers are AT&T and T-Mobile, plus smaller regional providers. If you have a phone on one of these providers, it’s a GSM phone, but that doesn’t necessarily mean you can use your phone in Europe or elsewhere.

There are four different radio frequency bands used by GSM phones. Think of these bands as radio stations, and for you to make a call, you phone must be able to “tune-in” to the right station. Within the U.S., North America and much of the South America, the GSM bands used are 1900Mhz and 850Mhz. Most the rest of the world including Europe, Asia, Africa, Australia and some parts of South America (i.e. Brazil) use the 900Mhz and 1800Mhz bands. (See this world map of GSM band use for a visual of what bands are used where.) Since there are four bands used world-wide, if you want a phone which works in every country, you need a quad-band GSM phone. Most older or cheaper phones are only dual-band, either 850/1900 (in the Americas) or 900/1800 (elsewhere in the world). Some phones are tri-band, usually 850/1800/1900 band if purchased in the Americas, giving you that extra band for some coverage abroad. For example, in the UK, the Orange and the T-Mobile UK service providers use the 1800Mhz band exclusively (no 900Mhz band), meaning you could use your tri-band phone on their networks without worry. However, as a general rule, most providers use both the 1800 and 900 bands, so you really need both if you want full service coverage. To find out which service providers use which frequency bands in the country you’re going to, go to this page at GSM World and click on the country in question.

If you travel to foreign countries often and want a phone that gets a signal anywhere, you want a quad-band GSM phone. Fortunately, these phones are becoming more and more common, and most of the higher end GSM phones by Motorola, Blackberry, Samsung, Nokia, Sony Ericsson and all versions of the Apple iPhone are quad-band GSM phones. To find out if your phone is quad-band or not, go to and search for your phone model. If under “Modes” is says “GSM 850 / GSM 900 / GSM 1800 / GSM 1900” then it’s a quad-band phone and you’ll get coverage in almost any country in the world.

Special Cases: Japan and South Korea

If you’re headed to Japan or South Korea, know that these two countries have no GSM service providers at all, and instead use a wireless technology known as W-CDMA. However, this doesn’t mean your phone won’t work there. Any phone which is marketed as 3G (i.e. the iPhone 3G) actually uses the same W-CDMA technology found in Japan and South Korea, although once again we run into the issue of frequency bands. Japan and South Korea use the 2100 band, the same band used in Europe and most the rest of the world outside the Americas for 3G data. The US and Canada use bands 850, 1900 (AT&T) and 1700 (T-Mobile). In addition to these bands, your 3G phone may have the 2100 3G band as well. Check your phone on If it says your phone has the W-CDMA 2100 band, it should work in South Korea and Japan. Since it’s apparently difficult or impossible to get a prepaid SIM card in these countries, you may need to roam using your home provider or using an international prepaid SIM card in order to get service. With this in mind, if you’re going to Japan or South Korea for an extended period, you may be better off buying a prepaid phone there.

Regarding Data Service

Since we’re using our phones more and more to check our email and get on the web, you may want to know if you’ll be able to use your phone for such things while abroad. The older, slower, 2G data services known as GPRS (the slowest) and EDGE (slightly faster) work over GSM, so if your phone has the right bands and the ability to make calls overseas, you’ll also be able to use data as well, as long as the service you’re using offers it. 3G service, however, is another story, since it uses W-CDMA technology instead of GSM. (This will be a repeat if you read the bit above on Japan and South Korea.) Europe and most the rest of the world uses the 2100 band predominantly, plus the 900 band in Australia and New Zealand, for 3G. The US and Canada use bands 850, 1900 (AT&T) and 1700 (T-Mobile).

To save you the counting, that’s five different 3G bands used throughout the world, which means if you really want a phone that will pick up a 3G signal on any carrier in any country in the world, you need a penta-band 3G phone. At the time of writing a handful of high-end Nokia phones featuring all five 3G bands, including the Nokia N8 and the Nokia C7 smartphones. Most other 3G phones will only have the bands used by the provider you bought the phone from (i.e. AT&T’s 850 and 1900 bands) plus the 2100 which is used so prevalently elsewhere in the world, and for most people this will be fine. If you’re going to Australia or New Zealand and plan on using 3G data, you may want to consider getting a phone with the 3G 900 band. If you’re going to Columbia, Costa Rica, Dominican Republic, Ecuador or Mexico, be aware that these countries use the 3G 850 band exclusively. If you need 3G service in the country you’re going to, check the GSM World coverage page, find the country in question and see what 3G bands are used there. Then check on to see what W-CDMA bands your phone supports and make sure you have a match.

Note that if you buy a prepaid SIM card to use abroad (more on this below), it may or may not allow data service, so if you need data access, check first to see if it’s offered by that provider. If data service is available, you’ll also need to change your phone’s data settings in order to access the new provider’s data service, so if you aren’t comfortable digging in to the settings pages of your phone, you may want to have someone at the store where you buy your prepaid SIM card help you. And remember, once you’re back in your home country, you may need to change these settings back again for using data with your home provider.

Current Conditions

Keep in mind that if you’re going to take your phone to other countries, you need to be able to charge the phone in those countries. Most quad-band phones sold today should come with chargers that work on electrical current ranging from 100V to 240V – a feature known as auto-sensing or switchable voltage, however, it’s always good to check your charger to make sure. You can determine what voltage your charger accepts by looking at the small print on the charger itself. If it says “INPUT: 100-240V” it is auto-sensing and you can use it anywhere. If it says “INPUT: 120V” or “INPUT: 100-120V” you can check this World Electric Guide to see if the country you’re headed to is using 100-120V electrical current. If your charger only takes 120V, plugging it into an outlet in Europe or Asia will fry it, so you would need a different charger (although you’re probably better off putting that money toward a new quad-band phone). You can also use the guide mentioned above to determine the type of electrical outlet plugs used in each country, since there’s a good chance you’ll need a plug adapter.

Roaming Internationally: An Expensive Option

Assuming you have a quad-band cell phone with an auto-sensing charger, you are set to use your phone overseas as long as your service provider has international roaming in the country you’re traveling to. If your a business traveler who’s just visiting for a few days and your company is fitting the bill for your phone use, or if you absolutely need people to be able to reach you through your regular phone number back home, this option will work, though at a hefty price: the cost for making and receiving calls while roaming abroad is usually in excess of $1.00 per minute, which is not exactly economical, especially if you’re going to be there for any length of time (check AT&T international roaming rates or check T-Mobile international roaming rates). The much more affordable alternative to this is to use a prepaid cell phone service in the country you’re going to, but to do this, there’s one more hurdle to consider.

SIM Cards and Unlocked Phones

One of the coolest things about GSM phones is that they use what are known as SIM cards (Subscriber Identity Module): small data cards about half the size of a stamp which are inserted in the phone behind the battery. With a GSM phone, your service and phone number is tied to this SIM card, and it can also store your contact list and text messages, although most newer phones store your contacts and messages on the phone itself, but with an option to copy them to the SIM. Has your phone battery ever died because you forgot to charge it, rendering it useless? With GSM phones, you can pop out the SIM card, insert it into a friend’s GSM phone and presto: your friend’s phone is now using your account, allowing you to receive your messages and make calls from your number.

This also means you can put a different SIM card in your phone, such as a prepaid SIM card purchased in when traveling in a foreign country. This is where the final hurdle comes in: the service providers don’t like the idea that you could buy a phone from them and then switch to another provider using the same phone. They want to keep you on their service, so they often “lock” the phone electronically to prevent you from using a SIM card from a service other than their own – something known as a SIM-lock. If you have a GSM phone, there’s a good chance it is SIM-locked to whatever service provider you bought it from (i.e. T-Mobile). You can still do the SIM-swap trick mentioned above if your friend is using the same service provider, but a SIM-locked phone won’t work if you put in a SIM from a different provider. The good news is that GSM phones can be purchased unlocked or unlocked after the fact – sometimes for free, sometimes for a small fee, depending on the phone and service provider.

First, it’s good to check if your phone is actually locked by putting a SIM card from a different service provider into the phone and powering it up. For example, if you bought your phone from AT&T and your friend is on T-Mobile, try swapping SIM cards and powering up your phones. If you receive an error when it starts up, your phone is locked. If so, the next best step is contact your provider about getting the phone unlocked. T-Mobile or AT&T have been known to do this for free if you tell them you’re traveling to another country, though they may only do it after you’ve had your services for a certain period of time (i.e. 90 days for T-Mobile). If you get a stubborn customer service rep who insists that you don’t need to unlock your phone because you can roam on their service, you might them you’re going to some small country where they have no roaming partners. (I once had to tell an AT&T service representative that my friend was going to Bhutan in order to get her phone unlocked). If they still refuse after multiple requests (it never hurts to call back and ask someone else) and after suggesting that you’ll cancel your account unless you can get your phone unlocked, then search Google with “unlock” and your phone’s brand and model. There are several places that will unlock your phone for a fee, although some phones can easily be unlocked for free, depending on the manufacturer and model. The other option is to take it to a mobile phone shop when you arrive in the foreign country and ask them to unlock it. If you’re buying a prepaid SIM card from them, you can probably convince them to unlock it for free (and if they say won’t unlock it for free, head for the door to find another shop – and don’t be surprised if they suddenly change their mind.)

Note to iPhone users: AT&T simply won’t unlock your iPhone, so don’t bother asking. You’ll have to do it yourself, and there’s plenty of info on the net about how to do this. Also, if you have an iPhone 4 and you do get it unlocked, know that you’ll have to hack any replacement SIM card you use down to the micro-SIM size used in the iPhone 4. (You iPhone users get all the fun stuff… )

Prepaid SIM Cards

With an unlocked quad-band cell phone, you can go to another country, insert a prepaid SIM card from any service provider in that country and then make calls at the same rates the locals pay (no roaming fees) and receive calls on a local number, which will make it easy for new friends to contact you (it’s rather impolite to expect someone to make an expensive international call to reach you when you’re in the same city). With a prepaid SIM card, all costs come out of your prepaid credit. Usually your prepaid SIM card will come with some credit so you can start making calls right away, then when your credit runs low, you can “top up” to add more by buying refill cards at gas stations, convenience stores and mobile phone stores. Outside of North America, mobile phone billing is a bit different: you are charged for outgoing calls and text messages, the costs of which are deducted from your prepaid balance, but all incoming calls and text messages are free (yes, free). The caller or person messaging you pays the bill; you pay nothing. This means that if you just want a phone with you so that people can reach you while you’re abroad, you can buy a prepaid SIM card, put it in your phone, give your number to whomever needs it and talk as long as you want when they call. (Note that for the calling party, calls made to foreign mobile phones are often far more expensive than calls to traditional land lines, usually over 20 cents per minute.) You can continue to make and receive calls day after day until your credit expires, which is anywhere from 30 days to a year, depending on the service provider’s terms. To extend your expiration date, just add more credit.

To check out the various prepaid service providers and their rates in the country you’re headed to, check out the listings at

International SIM Cards

You can find SIM cards which are marketed as international SIM cards. There’s list of them on However, when you check the rates and read the fine print for all these international SIM cards, it becomes clear that they are not the most affordable solution. They may be convenient if you’re an international business traveler who is constantly jumping from country to country, but even then you would probably pay about the same amount (if not less) to roam internationally with your home service, which would have the added benefit of allowing you to receive calls on your home number. Of all these cards, there is only one that I recommend – and I recommend it only for use as an emergency backup SIM card should you run out of credit with your prepaid SIM or if you need to make a call as soon as you land in a foreign country, before you have time to purchase a prepaid SIM card. That card is the Mobal GSM World SIM Card. You can see from their rate list that the per minute rate is far from cheap at $1.25 a minute for most countries in Europe. However, the advantage that this card has over other international SIM cards is that it’s post-paid with no expiration date, meaning you only pay for a call after the fact (you need to provide a credit card number so they can charge you) and, more importantly, the card should be active forever – hence being very well suited for an emergency SIM card. That said, if you haven’t used it in awhile, it wouldn’t be a bad idea to test it once in awhile before your travels to make sure it still rings when you call it.


If you already have a phone with a GSM service provider like AT&T or T-Mobile, find out what bands it has and what bands you need in the country you’re headed to. If it will work, get it unlocked if you want to use prepaid SIM cards instead of paying the hefty international roaming rates. If it won’t work, look into buying a quad-band GSM phone (with the 2100 3G band if you want 3G data in Europe, or if you want any phone service at all in Japan or South Korea). Get one that’s either already unlocked (Amazon has a variety of unlocked cell phones, many of which are quad-band) or one that you can get unlocked (some are more tricky than others) to allow the use of foreign prepaid SIM cards. With an unlocked quad-band phone, you can roam the world and stay connected with family and friends back home, as well as any new people you meet on your travels.