While several competing digital technologies are in use in the United States, much of the rest of the world uses GSM exclusively. Further complicating matters is the fact that the frequency band used by the GSM carriers in the U.S. (e.g., AT&T and T-Mobile) is not the same as that used in other countries.

Where Different GSM Frequencies Are Used . . . a Sample List
850 Band	900 Band	1800 Band	1900 Band
Canada United States	Africa Argentina Asia (except 3G* countries) Australia Brazil Europe Middle East South Pacific	Australia Europe	Canada Caribbean Chile Guam Latin America Mexico Peru United States
Visit GSM World for more specific country and provider information. *3G is the next generation of wireless technology. It has been widely adapted in Japan and South Korea, and phones sold in the U.S. will not work on the networks in these countries.

If you think you’ll need a phone outside the United States, there are several ways you could go. Here are a few of the main ones:

Option 1 — Get GSM service from a U.S. carrier and select a multi-band GSM phone as your handset. Carriers now offer multiple-band phones, including some that work on all four GSM frequencies (often described as quad-band). Visit our international page to compare phones that work on the dominant 900 MHz band. Before you travel, check with your carrier to make sure international service is enabled (it is often disabled by default for security purposes).

Example You subscribe to T-Mobile and have a phone that works in the 900 MHz band. Your phone will work where that frequency is available, and you will be billed by T-Mobile for calls made overseas. People can call you on your U.S. number and find you around the world, but it can be expensive; rates can be more than $1 a minute. Check with your carrier for packages that might offer a lower price.

Option 2 — Buy an unlocked GSM phone. GSM phones are controlled by a “brain” called a SIM card. SIM stands for “subscriber identity module.” If your GSM phone is unlocked, that means you can swap out SIM cards as needed. Your phone number will change with each new SIM card, so those calling your U.S. number will not be able to reach you. For some popular unlocked phones, click here

Example You buy an unlocked GSM phone that works on the 900 MHz band because you frequently travel to Europe. For each trip, you can purchase a prepaid SIM card at your destination from a network provider, or ahead of time from a U.S. roaming broker. The per-minute cost for this approach will be less than with option 1, and your incoming calls will often be free, but you will pay much more for the phone, as you are not purchasing it in conjunction with the wireless service of a specific U.S. GSM carrier.

Option 3 — Rent an unlocked GSM phone. At the end of the day, this is the same as option 2, except that you will only have the phone for the duration of your trip. This may be a good idea for anyone who makes infrequent overseas trips, but who doesn’t like option 1, either because their phone isn’t compatible (e.g., they subscribe to a CDMA technology carrier) or because they don’t want to pay the high per-minute rates from their GSM carrier.



Electrical current in many foreign countries is different from that used in the U.S. When you travel abroad, make sure you have the necessary converter and/or adapter to keep your phone charged.