the frequency spectrum of portable telecommunications.

Lawyers, lobbyists, legislators and increasing numbers of real people can now be paged or beeped or dialed directly wherever they are, thanks to a blend of new technology and deregulation of the radio frequency spectrum.

As the transistorized boxes proliferating on belt loops indicate, local area paging services are growing by 25 percent annually. Beepers are becoming as commonplace as Mark Cross pens -- and only a little more costly.

Bell Atlantic's Alex and Cellular One (which is partly owned by the Washington Post Co.) have signed up roughly 7,000 customers for cellular portable phones in the Washington area since the service began earlier this year. That's expected to grow to at least 70,000 by 1989.

A local firm faces a Silicon Valley challenger in a lesser-known sliver of the personal telecommunications market: wireless ticker-tape machines that list stock quotes.

Virtually every household in the country has a telephone. By the end of the decade, one in 20 households also will have a portable phone in the car. The basic beeper service -- the kind that sounds off telling you to call your answering service for a message -- costs less than $5 a month and is so cheap that some families tag their kids with a beeper to make sure they get home on time.

For professionals, of course, instant access offers a competitive edge. State-of-the-art pagers literally are little computers with the ability to store and display phone numbers and brief messages on a screen. Costs have declined while functions have expanded.

It's too early to say whether a critical mass of portable and personal communications devices actually has changed the way most Washingtonians do business. It surely has changed the lives of those already attached to their beepers and their portable phones.

Of course, there's always the potential for extremes in lifestyle changes. One person writes: "I have a relative whose hyper lifestyle revolves around his beeper. He keeps it by his pillow, much to his wife's disgust, and every waking hour has to call his beeper service to get his messages, even if it doesn't go off. He interrupts meals, conversations, etc., much to everybody's disgust. He always has urgent business, big deals to do, etc.

The interesting thing is the guy has been out of work most of the time in recent years. There's nobody to call him. He doesn't make much money, but obviously keeps his beeper service as a necessity or perhaps to preserve his sanity. Haven't seen him in a few months, but guess he's probably got a car phone by now."