It sounds like the worst possible sales strategy. Call people in the sanctity of their homes when they are trying to eat dinner, bathe slippery toddlers or get recalcitrant teens to do chemistry homework. Then try to sell them portrait packages or cemetery plots.

It works.

Telemarketers generated approximately $210 billion in sales to consumers last year, up from $195 billion in 1997. The industry is projected to grow at a rate of 7.3 percent annually for the next four years.

"It's a very successful form of marketing," says Chet Dalzell, spokesman for the Direct Marketing Association. And, with the trend toward deregulation -- consider the telecommunications, power and financial services industries -- he doesn't see the calls abating soon. Every time an industry is deregulated, he says, "there's a need to educate the consumer."

But perhaps you'd rather not be educated. Perhaps you'd like to try to rid your life of telemarketers altogether. It helps to know how they operate, and what your rights and options are.

Telemarketing today is the union of an age-old sales axiom -- it's easier to sell something if you talk directly to a potential customer -- with high-tech innovation. "Technology makes junk communications cheaper and more prevalent," says Jason Catlett, president of Junkbusters Corp.

Telemarketers often purchase information from list brokers, who ferret out names, addresses, telephone numbers and exhaustive purchasing profiles of potential customers. One such broker, InfoUSA, begins with the phone book white pages, then cross-references data from sources such as consumer surveys, warranty cards, birth and deed records and automobile registrations to come up with lists of homeowners, students, expectant parents, hunters, dog owners, millionaires, people with ethnic last names, even "self-improvement enthusiasts."

Telemarketers also "merge and purge" lists to zero in on customers. If they're trying to sell vacation time shares, for example, they might merge lists of subscribers to golf magazines, people who visit resorts and households with above-average incomes, then purge duplicates of names.

Once a list is refined through this "data mining," most telemarketing companies turn to the predictive dialer. This software-driven system dials numbers for sales agents, allowing agents' talk time to jump from 15 minutes an hour to 50. When the dialer reaches a live human being, it transfers the call to an agent, who simultaneously receives information about the customer on his or her computer screen. If no agent is available, the dialer automatically hangs up (and you thought someone was stalking you). These unanswered calls ("abandoned calls" to telemarketers, "nuisance calls" to everybody else) have so angered customers that the DMA has vol-

untarily instituted guidelines for the use of predictive dialers.

So, how do you protect yourself from unrelenting computer systems compulsively dialing your number? The best defense is to let telemarketers know of your profound non-interest. Sign up for the DMA's Telephone Preference Service do-not-call list. According to spokesman Dalzell, the list cuts national sales calls by 75 to 80 percent. If a company calls you, do not hang up once you realize it's a sales call (the automatic dialer will simply try again later). Instead, tell the sales agent you want to be placed on the company's own do-not-call list. Under federal law, if you receive calls from that company within 10 years, you may be able to sue for $500 per incident. You can also insist that you be taken off lists provided by brokers and credit bureaus. For information on all of these strategies, check out

Staying off telemarketers' radar screens completely is virtually impossible in our wired society, but you can give marketers less data to work with by not filling out questionnaires, entering sweepstakes, sending in warranty cards or registering software. You can also tell your credit card issuer not to share your personal information with companies you buy from. Avoid purchasing anything by telephone or catalogue (one information broker is working on a list of people who buy by phone); if you do, tell companies not to give out your name. And take care on the Internet: "Every keystroke you type, every click of your mouse, they can capture," says Phil Agre, a privacy expert at UCLA. That is data mining's new frontier.

If telemarketers are really getting to you, consider jumping on the privacy legislation bandwagon. Five states have passed do-not-call-list laws. Ten have barred telemarketers from blocking the display of their telephone numbers on caller ID screens. And Congress is considering a bill that would allow consumers to prevent their banks from selling their personal data to telemarketers.

Finally, a stunningly low-tech yet effective way to protect your privacy is as close as your wallet. "You can reduce the amount of data exhaust that you leave by paying cash wherever possible," says Junkbusters' Catlett. "But we shouldn't have to resort to this."

Elizabeth Chang is a copy editor in The Post's Outlook section.