PHILADELPHIA -- Some people see it as one small way to protect what's left of their privacy.
Others are fearful of uninvited contact from strangers.
A few are simply trying to hide.
Then there are those vainly trying to foil unsolicited calls from computers and marketers.
And so they cut themselves off by keeping their telephone numbers unlisted.
Not just the rich and famous. Not just the cops and the fugitives.
Buoyed by a rising fear of crime and a rising number of commercial telephone calls, nearly one in three Americans now keep their telephone numbers unlisted.
In Philadelphia, the rate is even higher: 43 percent of people with a telephone in their homes pay $1.75 a month to keep the number out of print.
"In telecommunications, as well as in other areas, the concern for privacy grows and grows and grows," said Temple University's James Armstrong, a telecommunications professor in the department of radio, television and film.
"In some basic sense, that's what most of the people are searching for."
Others, however, see something darker at work.
"The lack of community -- that's what's really behind it," said Gerhard Falk, a sociologist at Buffalo State College in New York state. "People have become suspicious of one another," he said. "The unlisted rate is one symptom of that."
Urban areas are where the suspicion runs deepest and the need for privacy is most acute. Of the 10 places in the country with the highest unlisted rate, numbers 2 to 10 are in California, ranging from Los Angeles, 61.2 percent to Bakersfield, 52.2 percent.
"We don't know why" it's higher in California, said Kate Flynn, a spokeswoman for Pacific Bell. Customers, she said, cite the same issues of safety and security, privacy and avoiding sales calls. "In Beverly Hills, privacy might be the overriding issue."
But rates, she said, might also play a part. It costs just 30 cents a month to keep a phone unlisted through Pacific Bell.
The place with the highest percentage of people opting out of the phone book?
Las Vegas, at 62.3 percent.
"It certainly changes the perception of what the telephone system is about," says Armstrong. "The idea of having a phone that permits you to talk to anybody in the world has to be modified. It's a device that permits you to talk to one-third of the people in the world. The other one-third don't want to be talked to."
In the last few years, the rate has increased dramatically -- from 21.8 percent in 1984 to 31.1 percent last year, according to Survey Sampling Inc., a Connecticut-based company that compiles lists of telephone numbers for market researchers.
"We think it has something to do with the increase in telemarketing," said Beth Wallace of Survey Sampling.