If your cell phone’s a homebody

For onetime, short-term use, rent a world phone from your carrier. Prices are comparable with third-party phone renters, and you'll get to keep your number and voice-mail access. Expect to pay $2 to $3 a day to rent a GSM world phone or international CDMA phone, plus roaming airtime minutes.

For frequent or long-term use in GSM countries, consider buying an unlocked world phone. These phones, which start at about $50 from vendors like Mobal International Cell Phones, Cellular Abroad, 1-800 Mobiles, and Cellhire, often come with everything you need for your trip, including the appropriate SIM card for your destination countries, and AC adapters, so that you can safely plug your phone charger into a wide variety of foreign outlets.

After your trip, you can store the phone until you need it again, or use it as a spare phone if you have AT&T or T-Mobile (just move the SIM card from one phone to another).

Your regular carrier might offer world phones and international CDMA phones for purchase, as well. But they come with expensive service contracts and the GSM versions are often locked to prevent you from using SIMs from other carriers. On the upshot, if you rent a phone from a carrier, you will not extend your contract for the months you're away.

For frequent or long-term use in CDMA countries, use your current CDMA carrier, or switch to one at your next opportunity. If you're a frequent traveler to a CDMA country, such as India, Israel, and parts of South America, your best bet is to use a CDMA carrier such as Verizon and Alltel for home and abroad. (Sprint isn't really an option because it has very limited roaming agreements outside the United States.) If switching means incurring high termination fees for breaking your contract with another contract, continue renting.

When you do buy a CDMA phone, make sure that it has analog backup, also known as a tri-mode phone. This will maximize your roaming options in all foreign CDMA countries except Japan. Japan's CDMA network is unique and requires renting a special phone from your carrier. For more tips, see Survival tips for using cell phones internationally.