Europe has adopted GSM (Global System for Mobile Communications) as its mobile communications standard unlike the United States, which left companies to create their own standards, resulting in largely incompatible networks.
If you're traveling to Europe or most Asian countries and want to use a cellular phone but also wish to avoid roaming charges, the GSM standard makes it easy to buy a phone that works, but there are some things you need to know about getting an unlocked version that works abroad.
Because you need a device that can allow for dual-band reception on a GSM and Subscriber Identity Module (SIM) card and most phones sold in the United States are "locked" into one carrier and SIM card, you'll need to purchase an unlocked cell phone if you hope to get reception in Europe.
Unlocked GSM Phones and SIM Cards
To make cell phone calls in Europe you'll need an unlocked dual-band GSM phone and a SIM card. The countries of Europe use the dual-band frequencies of 900 to 1800 while America primarily uses 850 to 1900.
When shopping for an unlocked GSM phone, you'll want a tri-band 900/1800/1900 (or 850/1800/1900) or a quad-band 850-900-1800-1900 if you intend to use it in the U.S. as well as in Europe. You may use a tri-band 850-1800-1900 unlocked cell phone in Europe, but you'll be giving up coverage in the 900 band, which is the most common band for international cell phone communications.
Many companies in the US sell locked cell phones which provide only one SIM card option for use with each phone linked to one particular carrier, which means you won't be able to use these abroad. Unlocked cell phones, on the other hand, are what you need as they allow the use of any SIM card, as long as the frequency capabilities are correct.
Buying Ahead of Time
It's important to remember when traveling internationally that you should take care of all your phone-related needs before you leave U.S. soil, especially if you plan to keep your same carrier and use the same service abroad.
You can check your U.S. carrier to see what roaming costs will apply, but with the low cost of cell phones and international SIM cards, you might be better off just buying an unlocked cell phone like the LG Optimus L5, and you can also request that your carrier unlock your currently locked phone.
The postage stamp sized SIM card is the heart and brains of the cell phone and will need to be purchased from your carrier for the country you'll be traveling to before you depart. The SIM card will determine the phone's number and allow access to the services that particular SIM card supports. Prices vary with country and services, and with a prepaid card, you'll probably receive unlimited incoming calls from anywhere in the world, some free calling time, and fairly reasonable long-distance rates (around half a Euro per minute).
Where to Get Them
Not long ago you were best off purchasing your cell phone and SIM card in the United States from a dealer who specialized in selling and renting cell phones for use abroad. However, you can now typically get these from your American service provider, too.
One benefit of getting the card early is that the number of your phone is embedded in the card, so you'll be able to give that number out to family and friends and activate the SIM when you get to your destination. You can easily add calling time to the original SIM so you don't have to change numbers each time you run out of call time.
These days it's also not hard to just go to a country and buy a SIM card at a very reasonable price. The Italian cards, for instance, are good for a year, have free incoming calls and messages, and allow you to purchase minutes as you go or refill from any of the many outlets, including newsstands, that recharge phones.
You can also rent a GSM cell phone, some of which come with auto rentals and leases. However, the rent on the phone along with the high usage rate often makes purchasing a GSM phone a better deal; you can likely save enough to pay for the phone on your first trip if you make several calls.