Anyone traveling abroad this summer must be reeling from shock. Places like Europe were expensive even in the old days. And that was before the Almighty Dollar had become the Yankee Peso. But your biggest sticker shock may not come until you get home and open your cellphone bill.

        Cellphones are invaluable when you travel. It's fantastic to know that folks back home can reach you if they need to, no matter where you are. Gone are the days when Americans in Paris had to visit the American Express office near the Opera to hear that Aunt Jane had died.

        But using a cellphone overseas can be cripplingly expensive. The roaming charges are eye-watering. I remember getting stung once for a three-figure sum over a long weekend.

So if you are about to travel abroad this summer, here's a money-saving tip. Leave your cellphone at home.

        Instead, use the Internet to route calls to a local prepaid cellphone in the country you're visiting. This sounds complicated, but it's surprisingly easy and can save you a fortune. I am currently in London and I just set it up myself.

Here's how:

Step 1: Before leaving the U.S., open an account with a Voice over Internet Protocol provider such as Skype (www.skype.com), Gizmo Project (gizmo5.com), or Truphone (truphone.com). These allow you to make and receive phone calls cheaply over the Internet. I've used all three of these services: They all seem fine. I'm particularly impressed by the value offered by Gizmo and Truphone. There are plenty of alternatives, as well.
Your VoIP account should also come with an ordinary U.S. landline phone number, letting people call you from a regular phone. (You may have to pay a small amount for this number). Give this to those who may need to reach you, and leave it on your voicemail as well.

Step Two: When you arrive at your overseas destination, buy a cheap prepaid cellphone. In Europe you can pick up a working local mobile on any shopping street. (Incidentally, from my experience, doing it this way seems much easier than trying to order a cellphone in advance over the Internet).
        Alternatively, you may be able to use your U.S. cellphone with a local SIM card. But the phone will need to be a model that works on overseas networks. And you will need to get your U.S. cellular provider to "unlock" it so that it will accept SIM cards from other companies. Contact your U.S. provider for details.

Step Three: Get onto the Internet, log in to your VoIP account, and set it up to redirect all calls to your new prepaid cellphone number. Most VoIP services have his facility.
        The result? If someone back home wants to reach you, they can simply call the regular, 10-digit U.S. phone number associated with your VoIP account. Their call will then automatically be routed, cheaply, via the Internet to your new cellphone.
        How much it will cost will depend on which services you use and where you are. But it is likely to be cents per minute rather than dollars. Folks back home will only pay for the U.S. leg of the call.
I've just started experimenting with this and so far it's working well. My Wall Street Journal cellphone remains -- switched off -- in my suitcase. (Yes, I'm saving Mr. Murdoch money.)