f you thought one room in the house offered an escape from ringing telephones, forget it. The Bell System wants to install one in your bathroom.

American Telephone & Telegraph Co. will announce plans Thursday for a major marketing effort to encourage Americans to buy telephones for the bathroom. The goal is simple: AT&T wants to raise the average of 2.7 phones per home to somewhere over three per home.

"There is a resurgence of decorating bathrooms in American homes today," said Stanley Clow, assistant vice president for residence sales and services at AT&T. "We see quite an opportunity in the 100 million bathrooms in the nation's homes."

The campaign will be unveiled at the headquarters of American Standard, a leading bathroom fixture firm, where Bell will display what it calls "fantasy bathrooms" designed by a Bloomingdale's staff member. Also appearing at that "celebration of the bathroom of the '80s" will be Dr. Judith Kuriansky, a New York psychologist and television personality, who will outline the growing importance of the bathroom for trendy Americans.

AT&T advertising campaigns will follow displays and brochures touting bathroom phones in phone center stores and even at home improvement showrooms and trade shows.

"The once inviolate taboos on bodily functions and intimate elements of personal hygiene are falling away as people come to regard these without embarrassment as part of the human condition," Kuriansky said in prepared remarks. "Therefore, the bathroom, where these needs are taken care of, is being opened up as well."

According to Kuriansky, the nation's interest in the bathroom is tied to the exercise boom. Americans are putting large tubs, massage tables, and exercise equipment into their bathrooms and pampering their bodies more than ever, she observes.

"All of this openness in bathrooms is not to imply loss of an intimate environment," she said. "On the contrary, new ways in which bathroom areas are being used only increases the opportunity for total privacy and self-awareness."

In this new setting, she added, individuals "are likely to want to communicate comfortably with others, and the bathroom telephone promotes that opportunity."

Although Kuriansky looks at tub talk from the psychologist's viewpoint, Bell sees dollar signs.

AT&T will sell 1.8 million to 2 million designer phones this year and would like to sell more; its push into the bathroom is a small measure of how committed the company is to conventional aggressive marketing.

With telephone sales picking up across the country, the breakup of AT&T only a year away, and the company about to inaugurate its separate new products subsidiary -- named American Bell -- company officials clearly feel a certain pressure to grab the consumer's attention.

Increasingly, AT&T seems to be getting squeezed, especially at the lower ends of the marketplace by retailers such as Tandy's Radio Shack, which are selling relatively inexpensive, lightweight phone units by the thousands. In fact, it is estimated that Americans will purchase some 3.7 million phones this year, about 17 percent more than last year, according to the North American Telecommunications Association, the trade group that represents most of the competition.

In years past, AT&T -- and most of American business, for that matter -- would not have mentioned the bathrooom. But on the other hand, AT&T was not much of a marketing company, either. "As we move into the competitive marketplace, we're looking at all alternatives," Clow said. "We have pushed phone use in sleeping and living areas, but it never occurred to us that the bathroom was a place where people really spent time and needed a phone."

As AT&T's product line grew simultaneously with the development of the $4 billion bathroom decorating and construction business, the new campaign seemed logical. "We're taking advantage of a trend," Edwin Langsam, an AT&T media relations manager, said. "We want to be a part of helping our customers make a statement about bathrooms," said Clow.

Company marketers know they're in for some needling about the program. "I'm sure some people -- pardon the expression -- will be taking pot shots at us," said Langsam, "but we're very serious about it."