A credit card that won't work for online purchasing unless it hears its master's voice? Sounds impossible, considering the difficulties inherent in voice recognition—never mind the challenge of cramming all that technology into a little plastic rectangle not much thicker than a piece of paper.

But Beepcard Inc. has very nearly done it. The company has devised a microphone, loudspeaker, battery, and voice-recognition chip small enough to fit into a credit card—almost. The prototype card is three times thicker than a regular credit card. But the company plans to use smaller chips to eliminate the extra girth.

The important stuff, though, works just fine. The card won't activate unless the user presses a button on the card and then speaks the correct password—in the correct voice. Once it's authenticated the password and voice, the card sends an acoustic ID signal to the online server via the computer's microphone. No reader hardware required, and it works from any computer.

It's a big improvement over Beepcard's earlier anti-fraud card. That one has a loudspeaker for sending the authentication signal, so the server can tell that the user has the card—and not just the card number—in hand. But with no microphone onboard, the card can't verify that the person holding the card is the rightful owner.

What finally got voice recognition technology to this point? Probably market pressure. For example, consumers have long been pushing for voice-activated devices for the handicapped. And cell phone fans have insisted on secure, hand-free units for safer use while driving.

The result is that voice recognition technology is now poised to help eliminate not just stolen credit cards but stolen identities. Now if they could just get your dog to listen to your voice.

Contact Alan Sege, Beepcard Inc., Santa Monica, CA; 310-493-8032, www.beepcard.com.