While internationally capable cell phones make calling home from abroad convenient, they're not always the most economical choice. For travelers looking for inexpensive alternatives, there are several options: new internet-based voice services, callback services and one of the most low-tech -- and low-cost-- options: prepaid calling cards.

The big news in calling home cheaply is "voice over internet protocol" (VoIP) services like Vonage (www.vonage.com), which is based in Holmdel, N.J., or Skype (www.skype.com), a company based in Luxembourg that was recently purchased by eBay. Since VoIP services generally work best with a broadband or wireless internet connection, they are recommended for travelers who want to make calls from fixed locations, such as their hotel rooms or a conference room—although they can also be used from internet cafes, or wireless hot spots if you have a notebook computer. (Some specialised VoIP services or phones like Wi-Fi Utstarcom F1000 phone will only work at 'open' hot spots that do not require a user name or credit card.)

VoIP works by digitising your voice and sending it via the internet to the other caller, who hears it on his PC's speakers, or by routing it through regular telephone lines to anyone's standard phone line.

"VoIP is great if you know you'll be close to high-speed data lines," says David Rowell, founder of the Travel Insider, a Web site and online newsletter that focuses on travel and travel-related technologies. But, Rowell adds, "it's problematic if you're on dial-up," in part because of insufficient bandwidth and speed, which may result in voice distortions.

VoIP is especially good for travelers with access to the internet who want to talk a long time or have friends or associates who have VoIP accounts.

Alternatively, Skype allows users to sign up instantly and start calling right away, as long as they have computers that can connect to the internet. Signing up with Skype is free, unless you want to call non-Skype phone numbers, in which case you'll need to purchase SkypeOut credits for 10 euros.

Among the plans that Vonage offers is a US$14.99 monthly plan that includes 500 minutes of calls to the United States, Puerto Rico and Canada, and a $9.99 a month SoftPhone option that allows subscribers to use their PCs or Macs to make and receive calls.

While many VoIP services allow you to talk free to other computer-based VoIP users, calls that need to originate (someone calls you) or terminate (you're calling mom) using a standard (non-Internet) phone will cost money. But since the majority of the call transport is done via the internet and the connections into and out of the internet are typically done as local calls, the rates are astonishing low.

Calling cards
"As high-tech obsessed as I am, I still use calling cards when traveling because they are typically one of the least expensive ways to call home," says Rowell.
Calling cards provide the ultimate in flexibility for calling home, since they can be used from most locations -- including pay phones, cell phones and landlines. They're also good for travelers who don't carry computers and who change locations frequently.

But be aware that not all calling cards are the same —especially when traveling overseas. "Some calling cards are basically shams," says Rowell, who typically purchases prepaid calling cards from local convenience stores or news kiosks when he is traveling. "They don't time the minutes accurately or you don't get what you paid for."

When buying a calling card overseas, Rowell recommends shopping around for the best rates. He also suggests buying a low value card first and confirming that the rates are as promised and call times are measured accurately. "Some cards have hidden fees that are only apparent after making some calls" he said.

It's also a good idea to compare the rate options associated with different cards, travel or while you're on the road. Some charge a per-connection fee as well as a per-minute fee (for example, a call with AT&T's USADirect plan and its calling card incurs an 89-cents-a-call surcharge). If you make a lot of short calls, the per-connection fees can add up quickly. Alternatively, MinutePass provides low rates (for example, 14 United States cents a minute from Canada to the United States) without a connection fee.

Callback services
For travelers staying abroad for long periods of time, and who plan on initiating lots of outgoing international calls, callback (or return call) services offer a relatively inexpensive alternative to direct-dial calls and frequently even prepaid calling cards.

Callback services operate as one might expect -- you place a call from a foreign location to a "trigger" number (a connection to the callback services' computers), let the call ring once and then hang up. The computer than calls back (from the United States, using much lower, predetermined international rates) and prompts the user for his or her account number and the number to be dialed and then makes the connection once the account has been verified.

Instead of expensive direct-dial charges, the user is charged a predetermined and frequently much lower price for the long-distance call. For example, a call from Brussels to the United States, using Telestial's (www.telestial.com) callback service would cost USD17.1 cents a minute. There is no cost for signing up with Telestial and you're billed only if you use the service.

"Callback services work well anywhere, but we find customers using them primarily in places like the Middle East, Africa, or Latin America where it's expensive to make a direct-dial international call," says Ken Grunski, chief executive of Telestial, which sells return call services, prepaid calling cards, mobile phones and more.

—NY TIMES