Make the Right Call

Unlocked means you can change the SIM card (it stands for subscriber identity module) that holds the phone's number and subscription information. You can replace your U.S. card with a prepaid SIM card that gives your phone a temporary local number with a foreign carrier.

Because you can buy SIM cards with prepaid minutes, no contract is needed. Costs range vastly, but SIMs generally start at about $6.50. How long those minutes last depends on where you call.

Uh-Oh, Your Phone Doesn't Work Overseas. So Buy One.

If your phone won't work overseas, you can always buy a cheapie for short-term use.

An inexpensive (and risky) way to do that is to buy a used phone on eBay in which you can install a SIM card. Make sure it's "unlocked" and can take a foreign SIM card, and works where you're going. Buying a used phone "as is" from a stranger can be dicey, but prices can run under $20, including shipping.

Less risky is to shop for a phone when you arrive at your destination. It's generally best to skip the kiosks in airports and head for a big-box store or even street kiosks, which sell inexpensive phones and SIM cards. For example, a prepaid-minutes phone from the U.K. carrier Orange, usable throughout Europe, costs 19.99 pounds, plus 10 pounds' worth of required minutes. That's about $60; prepaid minutes are charged at different rates, depending on where you call, but vary from 20 to 50 pence (about 40 cents to $1). There are 280 Orange shops in the United Kingdom; for a store locater, go to http://www.orange.co.uk/. Or you could buy one in advance online and have it waiting at your hotel when you arrive.

Another option in London is to buy a pay-as-you-go phone from a shop that represents several providers. The Carphone Warehouse ( http://www.carphonewarehouse.com/), which has stores throughout London, offers a Sony Ericsson J100i phone with 10 pounds' of minutes with Mobile World for about 25 pounds (about $50); calls to the United States are 5 pence (about 10 cents) per minute.

If you want to have the phone before you go, you can buy one from a service such as Mobal World Phones ( http://www.mobalrental.com/), which sells phones from $49, then charges by the minute. The rate may be no lower than your roaming charge. But roaming charges on your current phone can be cheaper than a common third option, a prepaid phone card, because you are charged only for the minutes used. Prepaid cards sell minutes very cheaply, typically in $5 to $10 increments, but unused minutes often aren't refunded.

Mobal puts in the SIM card, and it's good wherever you go. The company has an arrangement with overseas providers, and it marks up services that it sells to you as a single package. In the case of a phone you buy yourself online or overseas, change SIM cards in each country to get the best rate.

Uh-Oh, Your Phone Doesn't Work Overseas. So Rent One.

If your phone won't work where you are going and you don't want to buy, there are a lots of rental options. You may be able to rent from your carrier, which has one advantage -- your rental phone will have the same number as your regular phone, your voice- mailbox doesn't need to be changed and your preferences are preserved. Verizon will rent a GSM phone for $3.99 a day. The downside is that the per-minute call fee is roughly the same as roaming minutes, not the cheapest way to make a call.

You might find a better deal with a third-party rental. For example, Cellhire ( http://www.cellhire.com/) is renting phones for about $29 a week during its current promotion (there is almost always a special promotion).

Outgoing call rates aren't terribly low (about $2 to $6 a minute from the bulk of common tourist spots to the States), but they're possibly better than your own cellphone's and almost certainly better than a hotel phone. Cellhire also offers a premium Follow Me service, which transfers calls made to your home or office phone to your rental phone without callers being able to tell (in case you want to sneak out of the office and go to Spain without anyone knowing). That service raises the rate on incoming calls -- from $1.49 to $2.78 if you're in España, for instance.

A money-saving tip: If your company has rented from Cellhire, you can get the company discount. The government rate applies to anyone who works for a city or state (such as schoolteachers) and members of the military.