A public place, a placid moment, then: RING-A-RING!

Selma Silverstein couldn't take it anymore. On an evening rush-hour train a few months ago, she stood up and harangued a businessman who'd been talking on his cell phone for over an hour.

"You're a pig!" Ms. Silverstein barked to the loquacious commuter after he ignored her tirade.

Silverstein's boiling frustration with gabbing businesspeople reflects a growing problem in public areas. Even in the most placid of places - restaurants, plays, and operas, for example - the high-pitched bee-dee-beep of a cell phone pierces the calm at the most inopportune times. And with the rising chorus of complaints, many proprietors are asking: What to do about these ever-wired gadabouts?

Most people concede that cell phones are a fact of life and will soon be as ubiquitous as wristwatches. Today there are about 70 million users in the US, a figure that's expected to double by 2006.

But for some people, there's nothing more grating than the constant ringing. Others complain about the cavalier manner of many cell-phone users.

After her confrontation on the train, Silverstein, a New York psychotherapist, asked the Metro-North railroad to allot separate cars for passengers using cell phones and laptops. For now, the railroad has decided just to urge customers to be discreet, or talk near the doors.

But many believe a cell-phone-free zone on government-owned businesses, such as commuter railroads, violate free speech.

"Government regulation of cell phones in a public space would be hard to justify," says Charles Hinkle of The First Amendment Rights Committee.

Still, Mr. Hinkle believes exceptions should be made in situations where cell-phone use presents a threat to public health or safety. Most hospitals don't permit cell phones in patient areas since they can interfere with electronic equipment.

Private businesses, however, have free rein to regulate cell phones. Theaters and concert halls were among the first to try to silence them. Some actors' unions require that playbills print a notice to audiences to turn off their phones, and the United States Tennis Association has run a scoreboard message at all US Open matches requesting that cell phones be turned off.

It's common sense that talking on a cell phone while Pavarotti hits a high note or Pete Sampras delivers a serve is just plain rude. Yet it is not uncommon for people to forget to turn off their constant electronic companion, then rush to squelch the ringing just as Hamlet ponders Yorick's skull. But in restaurants and trains, where people are accustomed to a cacophony of noise, owners are reluctant to alienate their chatty customers.

CENSORSHIP aside, cell-phone etiquette has now become the province of the manners police. Peggy Post, an etiquette expert, and Southwestern Bell Wireless have teamed up to create a guidebook for cell-phone users.

Some restaurateurs are taking cell-phone etiquette seriously.

Danny Meyer, owner of some of New York's top-rated restaurants, bitterly remembers an incident when a diner noisily conversed on a cell phone while ordering. The ranks of garrulous gourmands have grown so much in the last year that Mr. Meyer now posts signs asking patrons to refrain from electronic discussions.

According to Meyer, these signs have made a huge difference. "They've empowered people to say something to a manager if it is troubling them."

Similarly, transit systems are combating cell phones with courtesy. This past year, New Jersey Transit printed reminders in its newsletters: "When using a cellular phone, speak in a low voice, so you don't disturb other riders."

But just as there are unrepentant smokers, cell-phone users, too, have their militant tendency. One 14-year veteran train commuter, who identified himself only as Roy, has been making business calls on his cell phone since 1990.

Roy says he clocks an average of two hours on his cell phone each day, mostly during his train ride to and from New York City - and has no plans to stop.

Does Roy ever worry about bothering fellow passengers? "No, most people are oblivious," he says.

(c) Copyright 1999. The Christian Science Publishing Society