With billions of dollars in credit card fraud every year, shoppers may be looking for more secure ways of doing their business. One such way is to use “temporary” credit card numbers.

They’re sometimes referred to as “virtual” or “disposable” numbers. They work in a variety of ways; while not foolproof, they may help consumers to head off abuse or misuse of their credit cards.

Most issuers of major credit cards will let you use a number (not the one on your plastic card) temporarily, often for just a single purchase. After that transaction is complete, the number becomes worthless to a thief or anyone else. The number is truly disposable, so even if a thief gets access to it, the number can’t be used for unauthorized purchases.

You use that number as you would your regular credit card, and your transactions show up on your regular credit card bill. Just as you save receipts from your regular credit card purchases, you should hang onto receipts from any temporary numbers you use.

Every issuer has its own rules for issuing temporary numbers; some tie the service to their online banking and may require you to sign up for it. Others offer a downloadable program that will pop up when you make an online purchase and ask if you want to use a virtual number. Still others require that you log onto their website when you want a virtual number.

What you should not do is click on anything in an unsolicited email offering you a temporary number. That’s likely a phishing scam, designed to harvest your personal information. Since the whole point is to keep that information away from the bad guys, don’t give it away to someone you don’t know. Also, when dealing online, make sure the websites you visit are the ones that truly match your intended destination, not some crook’s computer. Type in the address yourself, or use a bookmark if you’ve made one, rather than clicking on a look-alike link.

You also can request to use a disposable number more than once, and this is where things can get a bit tricky. Discover uses the term “secure account numbers,” and they expire on the same date your regular card expires. Bank of America calls its service “ShopSafe,” and its numbers expire after one year. Those types of temporary numbers are useful to people who want to use virtual numbers when they pay recurring charges.

Disposable numbers also can help prevent repeat charges that you don’t want. Say you sign up for a trial offer of some service at an introductory discount rate. Pay initially with a one-purchase number you’ve generated, and the vendor won’t be able to bill you automatically for a renewal.

The flip side of that issue concerns returns. A retailer who is unfamiliar with temporary numbers may hesitate to refund money on a number that’s no longer valid. A buyer heading into the holiday season might request that the temporary number be valid for two or three weeks into the new year, in case returns are necessary.

We’re told people who go through the process of credit repair often choose to use temporary numbers. The practice may give nervous consumers some reassurance, but they can’t defeat all fraud; as long as a disposable number is active, thieves might still make bogus charges with it. Some experts advise using only one-time numbers and that each number applies to a specific merchant.

Consumer Forum is a collaboration of the Bangor Daily News and Northeast CONTACT, Maine’s all-volunteer, nonprofit consumer organization. For assistance with consumer-related issues, including consumer fraud and identity theft, or for information, write Consumer Forum, P.O. Box 486, Brewer 04412, visit http://necontact.wordpress.com or email contacexdir@live.com.