Make the Right Call

There are scores of other cellphone rental companies to choose from, including Cellular Abroad (800-287-3020, http://www.cellularabroad.com/), Rent-a- Cellular ( http://www.rent-a-cellular.com/), InTouch USA (703-222-7161, http://www.intouchusa.com/) and Telestial (858-274-2686, http://www.telestial.com/).

Calling Cards

Calling cards are often cheap and require no special equipment, but you practically need a legal degree and a PhD in number theory to understand the cost per call.

Although some cards will entice you with low per-minute rates, they may boost the ultimate cost by having a "maintenance fee," which tacks on a daily, weekly or monthly charge. All cards assess taxes on each call, but some cards will charge more than the actual tax rate. The same goes for a mandated fee for calls from a pay phone. Some cards also charge a connection fee, added at the initiation of each call.

Check what increments of time the card uses to calculate charges -- meaning, how does it round up your minutes? Some charge in 30-second increments, some in three minutes or more. When you do the math, a card that charges a higher rate, but every 30 seconds, might cost less in the long run than a card with a lower rate that charges in three-minute increments.

Cards often have an expiration date, so don't be tempted to buy more minutes than you can use on your trip. Check to see if you get money back for unused minutes.

Even a card from a relatively easy-to-use one-stop shop, such as CallingCards.com ( http://www.callingcards.com/), requires a close read. While its cards are good for calls to and from any of 55 countries, you still have to pick from a variety of cards. They have subtle differences, such as having local access numbers or a single national toll-free access number. (This matters because some hotel phones, pay phones and mobile providers will block calls to national toll-free numbers.)

If you like calling cards, the easiest thing to do is just check to make sure there are no onerous charges, and if you aren't making long business calls, don't sweat the slight differences in costs. It won't amount to more than a few bucks over a week-long trip. Just buy the cards in small denominations so you'll be aware of how fast you are spending.

The VOIP of Reason

Potentially the least expensive option is VOIP (voice over Internet protocol), which carries calls over the Internet.

If you have a fast computer and a broadband connection, you can use a service such as Skype ( http://www.skype.com/), which offers free calls between registered Skype users worldwide. (It's free to register, too.) Calls to people outside the Skype network cost 2.1 cents a minute from more than 30 nations and regions (there's a list on the Web site) and up to 1.86 cents from remote places.

The catch is that you might have to pay for the Internet connection, which in a hotel can be pricey. And you have to carry a computer and headset, or a special phone, to use Skype. Equipment ranges from a free promotional headset to a $200 WiFi phone that uses Skype without the need of a computer.

There are ways to make VOIP calls that are less computer-dependent. For instance, you could use a service such as Jajah, which, like Skype, allows free calls worldwide between registered users. With Jajah, available in 85 countries, go to the Web site ( http://www.jajah.com/) and type in the recipient's number and yours. Jajah makes the connection, ringing both phones. Calls can be scheduled up to a year in advance. So you could set up sequential phone calls to a land line, and they would be free.

As with Skype, there is a small fee to call people who aren't Jajah members, which starts at 2.9 cents a minute from most developed countries to the United States but can go as high as 86.2 cents a minute from Cuba to the U.S.

Skype, Jajah and a company called iSkoot all offer software that can be downloaded to some mobile phones, allowing them to make cheap VOIP calls. Each works only on certain phones, and you'll have to check the Web sites to get a list, which changes frequently. In some cases, you'll need to have a data service subscription. Most recent GSM mobile phones can use data service, which is essentially a channel devoted to transmitting data rather than voice, but it can be a costly add-on.

Then there are companies that have combined calling cards, VOIP and mobile service into one, such as Pingo. Pingo ( http://www.pingo.com/) sells a virtual calling card. It's an account that charges like a calling card, but it simply recognizes your phone when you call through an access number and charges calling card-type rates. Pingo works in 35 countries, and calling rates range from 1.8 cents a minute between most industrialized countries to $1.81 a minute from China to remote places such as the Solomon Islands and Tokelau.

Putting It All Together

Combining several cost-saving strategies can help you reach your optimum savings-vs.-ease point. For instance, buy a used cellphone, get a low-cost SIM card, then make a local call to a VOIP-access number.

Voila! International calling for pennies above local calling.

Or better yet, have someone call you from the United States using Futurephone, a gateway number in Iowa that forwards calls to more than 50 countries (the current list can be found at http://www.futurephone.com/). Here's how it works: A friend calls 712-945-1112, then enters the international number where you are. It requires no sign-up and places no limitations on calls. If you are at a land line, it's free to you. All you have to do is answer.

It can't get any easier or cheaper than that.

Roy Furchgott writes frequently about technology. Carol Sottili contributed to this story.