Cell phone carriers handle international calls in a manner which is much different than domestic calls. All international calls are handled on a system called GSM, or Global Services for Mobile. This is a unified standard on which all carriers can work, and it is the reason a cell phone which works in New York City will also work in London, or Paris, or Sydney, and so on.

For a cell phone to work within the GSM standards, it must have an international SIM card. SIM cards are small chips which are placed inside of phones, allowing the device to connect to a wireless carrier in the area. International cell phones plans have SIM cards which are GSM-compatible and SIM card-unlocked, allowing users to connect to the proper international network to make calls.

There are two primary types of international SIM cards: prepaid and true international. A prepaid international SIM card is generally specific to a certain country, allowing users to acquire the same rates and benefits as locals. A prepaid SIM card for England, for example, will generally allow cell phone users to receive low local rates and free incoming calls. In effect, a prepaid SIM card is a temporary local card.

A true international SIM card, on the other hand, works all over the globe. These are best for people who will be traveling to different countries and thus will not benefit from a prepaid SIM card. The downside to an international SIM card is higher rates. Prior to buying an international SIM card, check the coverage areas to make sure you will be able to connect to the GSM network.

When you decide upon your SIM card, you will need to choose what sort of international plan you want to use. Most companies combine the SIM card and the data plan into one bundle, but others do not. Be sure you know the restrictions of your data plan, as you do not want to be subjected to outlandish fees. In general, it is best to make sure you have unlimited data and roaming.

Once you receive your SIM card, insert it into your phone if you are not using an international variety. As you travel, the SIM card will automatically connect to local networks, allowing you to access local calling rates and save a lot of money on charges while abroad.