T+L’s personal finance columnist, Jean Chatzky, answers your questions about monetary matters. This month: Cell and PDA service abroad.

Q: I'm heading to Europe this summer. What's the best way to get cell-phone and BlackBerry service for a reasonable price?—Rosario Welk, New York, N.Y.

A: You may not realize it, but with that question you're opening a technological can of worms. Bear with me as I walk through the basics to help you make the right decision for your needs.

Get a multiband GSM device In order to communicate via mobile phone or BlackBerry in Europe, and most other parts of the world outside the United States, you need a GSM device. If you're a customer of T-Mobile or Cingular, you likely already have one of these.

Unfortunately, your current GSM phone may still not solve your problem. It has to operate specifically on frequencies of 900 megahertz or 1,800 megahertz, or on those frequencies plus others (called a tri-band or quad-band phone). To figure out if yours does, ask your carrier or cell-phone maker.

Assuming your phone will work, you can activate international service on your phone. Once abroad, you'll be roaming, which means that every minute in, say, Austria will cost you $1.29. Spend a half-hour a day on the phone on a 10-day trip, and you're looking at roughly $400 in charges. Yikes!

Unlocking your phone, replacing your SIM card You can bring the cost down by buying local service in Europe. But in order to do that, your phone has to be "unlocked," allowing you to pop out and replace the SIM card that gets you U.S. service. T-Mobile will unlock your phone for you after you've been a customer for three months, or you can pay a third party, such as the Travel Insider (thetravelinsider.info) to unlock it.

Once your phone is unlocked, you need a SIM card for wherever you're going and prepaid minutes, which will reduce the cost of your talk time significantly. If you'll be visiting a few places on the Continent you can also get a card and minutes that will travel. It's best to buy your SIM card before you leave (try telestial.com); once on the road, you can purchase more minutes at most local cell-phone stores.

Consider your callers There's one other factor to take into account: incoming calls. If you use your U.S. service, you have to pay for them. If you use a SIM card with local service, you don't. The person calling you pays in both cases, however. If most of your calls will be coming from the States and you want your callers to dial a domestic number, then use U.S. service. But if most of your calls will be coming from the country you're visiting, local service is a better bet.

Buying versus renting So, what if you don't have a phone that travels?If you're an infrequent traveler, renting makes the most sense. You'll typically pay $5 to $10 a day for the phone, plus the cost of minutes. But renting means you'll be using a phone without your contacts and giving out a number that's not recognizable as yours.

That's why, if you're making more than one trip this year—or going for an extended period of time— you may want to buy a GSM tri-band or quad-band unlocked phone. Prices have come down on these devices, which now start at about $50 for a basic phone.

Mobilize your BlackBerry Finally, what about BlackBerrys, Treos, and other similar gadgets?Again, you need to be sure that yours is a GSM/GPRS device operating on the right frequency. Sending and receiving data can be expensive; prices can easily surpass $20 per megabyte. To keep the cost down, set your BlackBerry to display headers and subject lines only, so you can decide which messages are important enough to pay to open.

NEW DEPARTURES American Airlines recently inaugurated its first nonstop flight to China, into Shanghai, from Chicago's O'Hare airport. Not to be left stateside, Delta Air Lines will launch a flight from Atlanta to Dakar, Senegal, in December. The daily service will be the only direct flight to Africa with a U.S. carrier.

BEAR HUG After years of negotiations among loggers, environmentalists, and the provincial government, British Columbia announced the creation of the Great Bear Rainforest protected area, encompassing the largest intact temperate rain forest in the world. The 1.8 million hectare plot— 41/2 times the size of Rhode Island—is home to the endangered white Kermode bear.

NORTHERN EXPOSURE North Korea has invited several North American travel companies to the country for the annual Mass Games, a dance-and-gymnastics spectacular held from August to October. Tour operators such as Geographic Expeditions (800/777-8183; www.geoex.com; 10-day tours from $5,190 in August) are offering itineraries that include P'yongyang sightseeing and a visit to the Demilitarized Zone.