Nancy Pierce is "restraining" herself, trying to cut back from once every week to once every two weeks. But never would she let a whole month go by without calling in.

"I keep telling myself not to call, because all I'll do is be misunderstood . . . When you're calling in there is no way to be able to have that back and forth conversation. If someone misunderstands me, it's too late. I'm not permitted to call back. You're anonymous and that's a help, but if your voice gets recognized, you get known as a character."

Pierce, 52, a part-time writer/researcher, housewife and League of Women Voters activist is a "regular" on WAMU's "Kaleidoscope" call-in talk show (FM 88.5). Pierce's husband, Frank, jokes that he can't even get away from her outside the house -- he hears her on the radio when he's on the Beltway.

"When I start out listening to a show, I don't plan to call in," says Pierce. "If I did that, I would just be someone who likes to hear herself talk. Usually there is a question host Diane Rehm isn't asking or a question glaring at me that I just have to ask. Or there's a point of view that's not being stated."

Broadcasters call it "interactive radio," "talk product," a kind of user-friendly, first-name-only medium that depends on reactions and problems and the chutzpah to talk about them.

Recently on WHUR's "Newsmaker" (FM 96.3), host Kojo Nnamdi talked with the chairman of the Pan African Congress, a Palestinian professor from the West Bank and a representative of NORML. Last Monday, he talked about what was on the minds of the callers -- Georgetown basketball.

"We concentrate on hard news items," says Nnamdi, "but every two weeks, we do a 'lighter' feature -- male/female relationships, phobias or spring depression."

Even with last year's demise of all news/talk WRC, call-in talk shows are a pervasive part of American life. Even Luci Arnaz is getting into the act with her new CBS TV show, in which she plays a psychologist, advice columnist and radio call-in program host.

Mutual's longest-running act, Larry King (WTOP-AM, 1500) scoring 10,600 hours, has just been listed in the Guinness Book of World Records as the most heard broadcaster. NBC's Talknet syndicate, started in 1981 with 23 affiliates, has expanded hours to satisfy the current 229 affiliates nationwide.

ABC's Talkradio boasts 24 talk-show hosts, guiding discussion on everything from divorce to meditation. Of the estimated 80 interview programs in the Washington area, about 25 are call-in shows.

But while some hosts are bordering on "cult figure" status, as one Radio and Records writer put it, the better half of the show, the callers, remain a kind of nebulous mystery. At your next cocktail party, try this line, "Have you ever called into a radio talk show?"

Less than 1 percent of the population has.

Who are these voices? Depending on the show, thoughts are divided between "normal" and the strange/lonely, with most shows airing a combination.

"I learned that there were an awful lot of anxious people out there, who are afraid that the dawn will never rise," says former WRC "Allnight" veteran talk-show host Shelly Tromberg. "During the day there were more definitive responses. At night they were more searching."

When Diane Rehm opened up the phones with "what's your job?" taking 47 calls in 60 minutes, she heard from "people in the bowels of the Smithsonian, doctors, CIA, Defense Department, a blacksmith down in West Virginia. Less than a fraction of the callers are 'off the wall.' I have very little problem with that."

"I probably have the most intelligent audience in the world," claims WNTR (1050 AM) host Dr. Gabe Mirkin, a Georgetown assistant professor and CBS radio fitness broadcaster. "Most of the people who call in don't say they have a headache. Many of these people will say, 'I had an EKG and it showed inverted P waves and my LDL is high and I'm on dioxin. Should I be taking .2 or .3?'

"I have two crowds," says Mirkin. "I have the older people who are coming back to health . . . and then I have my young competitive person, my jock, who wants to know more technical information about becoming stronger or faster, or jumping higher or throwing further."

Generally, his most popular topics are, he says, intestinal gas and the female orgasm.

"Initally everybody thought we would get insomniacs, drunks and wackos," says Mark Feldman, director of public relations for Mutual Broadcasting. "We get lawyers, lots of reporters, Ted Koppel when he drives home, taxi drivers."

Almost every show has its regulars. "People have fingerprints," says Mirkin, "and they have voice prints." Although these regulars may endear themselves to the host, they are apt to be discouraged from calling too frequently.

Mirkin tells about one regular caller (when he was on Philadelphia's WCAU) who identified himself as "sometimes Henry and sometimes Harry. He was a brilliant character, but we didn't want to have the same callers. My producer said please stop calling.

"And then I was giving a talk in Philadelphia and this blind man came up to me and said, 'Dr. Mirkin, you are my hero.' It was Henry. Henry made a living selling pencils at the Philadelphia town hall. And I write to him all the time, and I told him he could call anytime.

"Suddenly he had a radio show that he could communicate with."

Larry King's "Open Phone America," 3 a.m. to 5 a.m., has its regular callers, "all harmless," says Feldman, "but a little different."

There's "the numbers man" who calls from a phone booth in Passaic, N.J., with baseball scores based on biblical interpretations. "We listen to him, we think he's funny," says Feldman. "But Larry always hangs up on him. He says he can predict scores, but he does it after the game."

There's "the Portland laugher," who, after the production assistant asks "where are you calling from?" and he says Portland, King gets on the phone, says Feldman, "and the guy just starts laughing." (Other callers have tried unsuccessfully to imitate the laugher.)

"Open Phone America is really the time to have fun," says Feldman. "Whatever's on people's minds. He won't take it during the other time. It's a barometer about how America feels about certain things. During the Goetz thing, AP called us to see how people felt about it."

Keeping opinion-type talk shows moving isn't a problem, say some hosts, if you pick the right topic.

"The most important benefit is that it a call-in talk show allows for debate with the listening audience," says Nnamdi. "When they call with opinions, we want to challenge those opinions. The purpose is to provoke our audience into thinking about those issues."

Others suggest that talk shows provide a haven for the conflict-addicted. Says one 31-year-old Washington author, a veteran guest of over 20 talk shows: "It's an easy form of confrontation. You're not facing anybody, and it's easier to fight with a stranger. It's definitely a medium that brings out the cranks."

Philadelphia WWDV host James Corea, whose most popular topic is weight loss, says it's hard not to laugh when you hear some callers' comments.

"I have had people, college graduates, tell me that they have eaten a full meal -- salad, soup, cheesecake, spaghetti, the whole nine yards -- and then they drank a glass of grapefruit juice and by doing that, they will look magnificent . . . Sometimes I do laugh."

Some talk-show theorists believe that the appeal of the programs may be in the chance to listen in on others' problems and conversations. "I think," says Tromberg, "it provides a surrogate family and a sense of community."

"Things that touched people's lives were clearly the way to go," says Dick Penn, senior vice president of NBC Radio Networks, who was instrumental in getting the network money to launch its successful national personal-problem shows.

"Audiences go away from the radio with some kind of information that may help them lead their life a little bit better tomorrow."