'I'D love to work for you," said a prospective nanny to me over the phone in 1988. "But I notice your area code is 818. You'll have to find someone else." Click.I am reminded of this once-upon-an-insult this week with the announcement that Los Angeles will become the first American city to have three area codes. At 2 a.m. this Saturday, an invisible, U-shaped stripe will be superimposed from Malibu on the coast through the South Bay and West Los Angeles - carving up 10 cities including that most prestigious of enclaves, Beverly Hills. The news has divided residents into three general camps:(1) city chauvinists who find the distinction a new reason to thumb noses at New York, Chicago, and others cities still with only two; (2) Chicken Littles who see symbolism for the further balkanization of an unmanageable metropolis, sprawling 14 million people over five counties; and (3) local officials barely suppressing smiles for being lumped in with other communities of the far more well-to-do. But Kathleen Flynn at Pacific Bell told me that although California's massive growth (840,000 in the 1980s) is behind the move, the need for three new digits reflects technological gains and lifestyle changes just as much. "Pagers, faxes, mobile phones, and computers with modems all make this the first area-code change in history dictated by technological growth," she says. The last time an area code was added here - 818 in 1984 - only about 10,000 numbers were needed for mobile phones and radios. Now the figure is 290,000. The city's 740 miles of freeways, aided by little in public transportation, make L.A. No. 1 in cellular-phone use nationwide. Still, there are more-than-usual questions of identity and eclat in a land of movie make-believe where image is paramount. "The striking thing about this city is how avidly and with what tone of alacrity we embrace imaginary boundaries to set ourselves apart," says Mike Davis, author of a new book on Los Angeles called "City of Quartz," When most of the San Fernando Valley was given the code 818 in 1984, he points out, the move actually helped coalesce a political movement that has sought the area's secession from the city. "I have never seen a city more status-conscious about such details," says Susan Warner, editor of a publication "Beverly Hills 213." "When I moved here, I dated a man who was crestfallen that my prefix denoted Beverly Hills, while his did not." Mr. Davis says the new dividing line will exacerbate already-existing status rivalry between communities in East and West L.A. In Beverly Hills, the upscale retail section of Rodeo Drive will become 310, prompting new moves to embrace the new number. Beverly Hills perfumer and retailer Fred Hayman, founder of Giorgio, has already trademarked the title "Beverly Hills 310.It's absolutely a much higher and more important number," he told me. "[Area code] 213 is in a sense the loser," notes Davis, "because 310 will become the new number of exclusivity." Ms. Warner - whose home one mile from work remains in 213 - says the whole thing is just inconvenience. "I think the phone company is testing to see how much money it can get for long distance," she says. The telephone company says the rates won't change. A sociologist who studies the social effects of technological change told me southern Californians are more persnickety than any community in the country about their area codes. "They identify with them the way other cities identify with their football or baseball teams," said James Katz, a researcher for the New Jersey firm, Bellcore. "Since they don't have roots as deep as those in other cities, this kind of shift makes it much harder to maintain a kind of geographical community," said Katz.