At the Commonwealth Women's Clinic in Falls Church, the receptionist drops the phone. Her eyes go wide. "There he is," she says.

Diane Wheeling has just been interrupted from telling a visitor how it feels to work at an abortion clinic these days. The voice on the phone is male, crackling rudely into her ear: "When you leave tonight, take everything you like -- because we're going to blow that place up."

The call came in a week ago Thursday at 12:31 p.m., another in a spate of ominous incidents at abortion clinics around the country, including 30 bombing and arson attacks since May 1982.

"Tell them no sirens," clinic administrator Nancy Dickinson instructed the police dispatcher. "The patients cannot take that."

In short order, two harried-looking Falls Church police officers, a mustachioed agent from the Bureau of Alcohol, Tobacco and Firearms and a bomb-sniffing German shepherd arrived to investigate the threat, the second received by the clinic staff since September. As with the previous call, the police found no explosives.

"We take it very seriously. They've been hitting these clinics all over the country, so why not here?" says the Falls Church deputy police chief, Maj. Timothy M. Toureau. "Personally, I'd be scared to work there -- wouldn't you? I would quit and find myself some other job. I'm not going to get blown away."

Dickinson, a registered nurse with a master's degree in health administration, is a tall blond woman with an air of command, a native South Carolinian who strews her talk with "darlin's." Distractedly gulping water from an otherwise pristine specimen cup, she says, "I'm telling you, darlin', you have to keep a sense of humor about this. Otherwise, you can't make it through the day. You have to smile through this."

She smiles brightly. "As you can imagine, everybody's just scared to death."

On the day of the bomb threat at Commonwealth Women's Clinic -- 56 hours after a real bomb, a few minutes into the New Year, destroyed much of the Hillcrest Women's Surgi-Center in Southeast Washington -- President Reagan issued his first direct condemnation of abortion clinic attacks and vowed to "do all in my power to assure that the guilty are brought to justice."

The same day, a score of clinic operators caucused at the Rockville headquarters of Planned Parenthood of Metropolitan Washington, which itself was bombed on Nov. 19 along with the Metro Medical and Women's Center in Wheaton, to talk about ways of coping. The next day, as if to mock their deliberations, someone set off three smoke bombs in the doorway of the Ophelia Egypt Clinic, a Planned Parenthood center in Anacostia.

"The job is stressful enough without having the added stress of worrying about your personal safety," says Rosann Wisman, executive director at Planned Parenthood headquarters. "I think people are anxious, jumpy. You find yourself wondering when and if . . ."

"For the first time in my life I have come face to face with actual fear," says Penny Smith, administrator of the demolished Wheaton clinic. "Prior to the bombings, I never felt physically threatened. Now I'm constantly looking over my shoulder. Sometimes when I get into my car, there's a moment of fear when I really don't want to start it."

Attacks on abortion clinics and their employes are nothing new, and the rhetoric of the controversy has long been violent. But figures from the National Abortion Federation, whose headquarters were bombed last July, reflect a fourfold increase in incidents over the last three years, suggesting that hot words are giving way to desperate acts. Recent episodes have included a kidnaping (of an Illinois clinic owner and his wife by the notorious "Army of God" in August 1982) and a decapitation (of an Alabama clinic employe's pet cat in November).

Although no one has been injured in the attacks of the last year and a half -- eight of them concentrated in the Washington area -- they amount to the biggest wave of antiabortion violence since the U.S. Supreme Court, in Roe v. Wade, declared the procedure legal. With the 12th anniversary of that decision approaching on Tuesday, Jan. 22, and activists on both sides gearing up to mark it with marches and rallies, advocates and detractors alike -- not to mention clinic staffers, patients and police -- are bracing for more of the same. Today the National Organization for Women is announcing plans for members to stay overnight in clinics on the weekend before the anniversary -- a suggestion that two abortion rights groups have already called irresponsible.

"Every time I hear that there's been another bombing, I think we're one step closer to somebody being hurt," says Peter B. Gemma Jr., executive director of the National Pro-Life Political Action Committee, an antiabortion PAC based in Falls Church. "Sooner or later some innocent person is going to be harmed by these fanatics. Sooner or later, God forbid, they're going to kill somebody. We're on the defensive, trying to explain how we don't stand for violence. It's bad PR, that's the bottom line."

Gemma, who has occasionally picketed Commonwealth Women's Clinic, a few miles down the road from his office, says the FBI should take over the federal investigation from the lesser known but widely praised ATF.

"These are not sporadic attacks. There's clearly a planned operation to bomb clinics in this country," he says, echoing such opposition groups as the National Abortion Federation, although investigators have yet to produce evidence of a conspiracy. "If the FBI isn't going after abortion clinic bombers, what do they exist for? The last time we heard from the FBI, they were selling secrets to the Reds."

By a quirk of commerce and geography, Commonwealth Women's Clinic nudges the grounds of Saint James Catholic Church, which frequently nudges back with antiabortion prayer vigils.

"If it ever went up, I would probably go with it," says the Rev. Robert C. Brooks, pastor of Saint James, whose wood-frame rectory stands about 100 yards from the clinic, across a parochial-school playing field. "My bedroom faces it on the back side of the house. We know that our windows would definitely go, because we're an older structure. It could possibly damage the convent windows, and the religious education center windows also."

The two-story red brick clinic building, a model of inconspicuous architecture, might escape notice -- except that it's the former American Women's Clinic, the name still blazoned on the sign out front. Under that name it was operated by Dr. Chris Simopoulous, who was arrested last July on felony charges of scheming to perform abortion procedures on women who were not pregnant.

At about 2 a.m. on July 29, ATF agents caught a 32-year-old McLean man smashing through the clinic's windows. He was charged with misdemeanor destruction of private property, but the prosecution was dropped when Simopoulous, who had legal troubles of his own, failed to press charges.

Shortly before Simopoulous disappeared and became a fugitive in September, he sold American Women's Clinic. The property came complete with its own faithful band of protesters, who have been demonstrating there regularly for several years with parish permission, and a brand-new picket fence erected to keep them out.

Both protesters and clinic employes agree that the recent explosions have thrown a harsh light on the nonviolent demonstrations. David Peck, 24, a regular picketer at Commonwealth, says antagonists now sometimes ask him, "Have you planted any bombs today?"

"I don't feel that I'm in any physical danger," says Dr. Thomas H. Gresinger, the clinic's medical director, a diminutive gynecologist in a pale-green scrubsuit who has performed first-trimester abortions for the last 11 1/2 years. "I just find these people annoying and extremely presumptuous, that they can ignore the views of everyone else but themselves. I do mind the ones that hang over the fence, harassing my patients with grisly pictures of very late abortions. You should see these young ladies when they come through the door, collapsing in the nurses' arms one after another."

ChristyAnne Collins, 29, a "full-time advocate for the unborn," hangs over the fence. Rain or shine, on the mornings when the clinic schedules abortions -- about 40 a week at $170 each -- she is usually to be found atop a wooden platform on the parish's side, accosting staffers and patients as they climb the long staircase to the clinic's entrance.

"Excuse me, ma'am, that's a pretty coat," Collins calls out to an arriving nurse, who walks head down through the parking lot. "How many babies did you have to kill to buy that pretty coat?"

Nurse Wendy Hemingway says later, "Some morning I'm going to come to work in a mink."

The facility offers a range of gynecological services, and not all patients come for abortions. Some have appointments at the dentist's office on the first floor, where the receptionist has started asking the janitor to keep her company when she works late.

"Are you here to see the abortionist?" Collins calls out to another woman, resolutely climbing the stairs. "Please, let your baby live. We'll help you in any way we can."

A member of Christians Against Abortion, Collins has been skirmishing in the trenches for the last four years, conducting "direct intervention" and "sidewalk counseling" with would-be patients, steering them to antiabortion gynecologists and shelters for unwed mothers, picketing clinics (she was one of 46 protesters arrested for trespassing at the Wheaton clinic two days before the November bombing), heckling doctors and nurses and occasionally fighting the enemy hand-to-hand.

She's pressing a misdemeanor assault charge against Wayne Codding, landlord at Commonwealth and Gresinger's partner in Fairfax's Northern Virginia Women's Center, in Falls Church General District Court. On the morning of Dec. 13, she alleges, Codding grabbed her wrist, slammed it down on a fence post and tried to take her antiabortion leaflets. Codding declines to comment on the allegation.

"I have to say to you with real honesty that I feel real ambivalent about the bombings," Collins says. "I don't condone violence at all. But I know that not another baby will be murdered where those bombings are going on."

The Saturday after the bomb threat at Commonwealth, the protesters return in force. About 40 pickets -- some of them pushing baby strollers -- march back and forth across the driveway, parting ranks for cars. A few sing hymns. Others wave at passersby, acknowledging horn-honks with the thumbs-up sign. A woman and a boy, in the manner of charismatics, hold hands and pray in tongues. "N-n-n-n-n, yes amen, yes amen, yes amen," the woman chants. "Curse them, Jesus, curse them, curse them . . ."

"HUMAN GARBAGE," says a placard bearing a photo of a fetus in a bucket. "ABORTION IS OUR HOLOCAUST," reads a hand-painted sign dominated by a black swastika. Sharon Miesel, 33, ChristyAnne Collins' roommate and fellow activist, stands on the platform.

"Your baby's heart starts beating at two weeks," she cries at new arrivals. "Your baby feels pain at eight weeks. Don't go in there and let your baby die."

Most of the women hurry up the stairs. A few come up to the fence to accept Miesel's proffered leaflets. One, a 26-year-old dental assistant, whirls on Miesel and shouts back colorfully.

"I rise to the occasion," she says later with a grin as she waits for her appointment. "I'm amazed at how scared and upset people are getting. I'd like to see more people fight back and stand up to them. I wish I had a sign." She adds, "I'm here for a pregnancy test, and if I'm pregnant, I'll have the abortion today."

A man stands with the mother of a 14-year-old retarded girl who has been brought in for an abortion. At the top of the stairs, the mother watches the demonstrators and sobs. The man puts his hand on her shoulder. "This is just upsetting you. Go back inside," he tells her. "I'd like to jerk them up by the head," he adds.

Inside the clinic, administrator Nancy Dickinson is busy arranging escorts for patients who don't want to cross the picket line alone. "I've got no time to talk now, darlin'," she says, her smile replaced by a scowl. "The patients are just freaking out."

The fear is contagious. Tom Hill, an ATF public affairs officer, admits that he, too, sometimes feels "paranoid." He says he fretted recently when his wife made an evening doctor's appointment near an abortion clinic.

A part-time counselor from a bombed clinic pleads for anonymity: "I think of my name in the newspaper and all of a sudden I'm frightened." A nurse from the same clinic, unemployed since the bombing, says she won't return to work. Other clinic employes, however, say they are more angry than fearful -- and more committed than ever to providing birth control services.

"I'm really not afraid of them," says Fatemeh Gohari, administrator of Metropolitan Family Planning Institute in College Park. Along with her husband, Dr. A.N. Gohari, the medical director of that and two other clinics, she has been the target of telephone harassment at home, fielding abuse and death threats at 3 a.m. "I believe in what I'm doing. I'm not doing anything illegal. What they're doing is illegal."

The owners of Hillcrest Women's Surgi-Center, the latest clinic to be blasted out of business, have told employes not to speak to reporters. But at the 31-unit apartment building across Pennsylvania Avenue, where the shock wave shattered glass and cracked concrete, longtime resident Valerie Gadson has the jitters.

"Last night I kept waking up. I thought I heard a bomb sound," says Gadson, the mother of three. "It turned out to be one of these freight trucks hitting a terrible bump. When I go outside now, I'm still afraid, constantly looking around me. I just hope that place doesn't reopen. If it reopens, I believe that whoever did it is going to come back."

Penny Smith, administrator of the Wheaton clinic, complains of difficulty sleeping. "It's very hard not to take these things personally," she says of the bombing. "I have to keep reminding myself that it wasn't a personal attack on me."

Says Lisa Ammerman, a nurse at the Wheaton clinic, "I'm an optimist. Maybe that's not real smart. Of course, I do make sure I'm not being followed when I go home. I'm always checking my rear view mirror. I'm a little more careful on the telephone at home. I'm a little shorter with people who don't identify themselves."

The ATF says it has solved 12 of the last 30 attacks nationwide and, on the theory that the local incidents are connected, has distributed a drawing of a man wanted for questioning -- "a white male, 25 to 35 years old, 5-foot-8 to 5-foot-10 tall, with thinning brown hair and a thin build." It has also posted a $10,000 reward for information.

"I certainly sympathize with these people, and I certainly understand their feelings of anxiety," says the chief of ATF's explosives division, Daniel M. Hartnett. "Hopefully, we're going to be able to relieve their fear and tension."