Here's how it works: Given that more than 90 percent of telemarketing calls are placed with computer assistance, when either you or your answering machine answers the phone, the Telezapper emits a special tone that tells the computer your number has been permanently disconnected. Telemarketing companies that use automated dialing systems typically remove disconnected numbers from their calling lists, and as your phone number is eliminated from more and more telemarketing lists, you'll notice fewer calls. Of course, not all telemarketers use predictive dialing systems, and those that do will undoubtedly work to evade the Telezapper, but it can be a partial solution.

For the most part, regular callers are unaffected by the Telezapper, but it may "zap" calls from other organizations that use the same predictive dialing technology (such as charities, pollsters, and automated emergency weather systems) and from callers who use certain types of calling cards. (For more information, click FAQ, or frequently asked questions, in the left navigation bar.)

In our tests of the Telezapper, installation took just seconds. We plugged the Telezapper into our phone line and our phone into the Telezapper and then connected the AC adapter. It was that simple. There are no moving parts to wear out and no batteries to replace.

We field-tested the Telezapper for several weeks, and during that time, we noticed a significant reduction in telemarketing calls. Of course, this was not a scientific study, and we cannot with certainty attribute our results to the Telezapper, but the device seemed to work well for us.

The Telezapper includes a phone cord, power adapter, and instructions. Privacy Technologies backs the device with a one-year warranty. --Mike Bro