TELEPHONE customers in Hudson County, N.J., have a powerful service at their fingertips. They can trace calls, block unwanted calls, or learn a caller's number before picking up the receiver. ``As soon as you hang up from a call that you want traced, you have to immediately press the access code, *57, and then that call is traced,'' explains Barbara Walcoff, a spokeswoman for New Jersey Bell. A permanent record of traced calls, complete with the number of the caller, is then made at a telphone company office and given to police for investigation.
Call Trace, Call Block, and Caller ID are just three of a plethora of new features and services that regional telephone companies in the United States plan to offer within the next decade, all made possible by the computerization of telephone system.
In addition, businesses will be able to connect their computers directly to the telephone system and transmit information at much faster speeds. Digital-based services are scheduled to be offered soon to customers in New York, all of New England, California, and parts of Florida.
Across the country, 43.9 percent of the 123 million installed telephone lines are connected to such switches, according to a report by McGraw Hill Northern Business Information Entity.
For most telephone companies, the non-digital switches are the way of the past: ``[Everything] we are installing now is digital,'' says Jerry Johnson, New England Telephone's managing director of network planning in Boston.
For customers to use the computerized services, their telephones must be connected to these state-of-the-art, digital telephone-switching systems. In New Jersey, 40 percent of the telephone company's customers can take advantage of these services today, says Ms. Walcoff, a number that is expected to increase to 70 percent by the year's end.
While only 37,000 customers in New Jersey have subscribed to at least one of the new telephone services, says Walcoff, some features such as Call Trace can be used without prearrangement.
Already, the number of obscene and crank phone calls are down nearly 50 percent in Hudson County.
``It has had a chilling effect on people who may have thought about making crank phone calls,'' says Mr. Johnson. ``People know that their calls can be identified, so many would-be harassing phone callers are afraid to make those calls now.''
In the six-month period ending April 30, the phone company received only 236 requests to trace telephone calls, representing a 49 percent decline from the same six-month period two years earlier, according to a the phone company's June 1989 report to the Board of Public Utilities.
In 1988, an independent New Jersey study found that more than half of all telephone subscribers receive annoying or threatening telephone calls, whether or not they have unpublished telephone numbers.
Some citizens' groups, however, have questioned the deployment of the new technologies, saying they invade the privacy of people making telephone calls, by revealing their number. Oftentimes, says Colleen O'Connor, director of public education for the American Civil Liberties Union in New York, there are legitimate reasons to keep such numbers secret:
``An example might be if a woman is calling her kids from a battered-woman shelter, and calls her home, and her husband is able to find out where she is,'' says Ms. O'Connor.
At recent hearings before the Public Utility Commission in Harrisburg, Pa., operators of confidential hot lines said that people in need of help might not call if they suspected that their telephone numbers might be displayed on the hot line's telephone number.
``I think that it is the end of unlisted numbers as we know it,'' says Bob Smith, editor of the Privacy Journal. But, he says, ``in a way it enchances privacy by probably putting an end to anonymous harassing phone calls.''
Because of the as-yet unresolved privacy concerns, some regional telephone companies have decided not to offer caller identification features as part of their new service offering.
``[We] are still examining the issues surrounding that, and it is not part of the first deployment,'' says Ann Sizopoulos, a spokeswoman for Ameritech Services, which serves states in the northern Midwest.
BUSINESSES in the US are beginning to make use of the ability to automatically identify the number of a caller as part of a more sophisticated computerized service called Integrated Services Digital Network (ISDN), now in limited use but likely to expand.
``If you call an 800 number to order something from a catalog, or inquire about your credit card balance, or if you happen to subscribe to certain computer databases, it is quite possible that the company that you are calling subscribes to ISDN ... and is using the capability to capture the number that you are calling from,'' says Daisy Ottman, a media relations manager at AT&T in N.J.
A company that sells products through local representatives can use a customer's telephone number to automatically direct the caller to the nearest dealer in their area, says Ms. Ottman. Credit-card companies can use a customer's telephone number to automatically display his or her customer history on a computer screen when the operator answers the telephone call.
Companies can also preserve a caller's telephone number in a computer's memory bank and use it for telephone solicitation, cautions Mr. Smith.
The number can be recorded even if the telephone call is left unanswered.
Demand for ISDN has been ``remarkable,'' says Ottman.
``The service became available on July 4 of 1988.'' Today, she says, ``we have more than 300 customers who have either implemented the service or are in line for implementing the service.''
But ISDN's real advantage is speed. A 100-page contract, which might take 28 minutes to transmit with a conventional fax system, can be sent in less than 30 seconds using ISDN.
ISDN uses the same pair of copper wires that run from the telephone company's central office to the home or office, but with ISDN the wires become a high-speed interface directly into the telephone company's computers. Down the wire passes a digital stream of 1's and 0's, which must be decoded by special ISDN telephones back into speech with a process that resembles the way music is played off a digital compact disc.
``The analog network is like a dirt road. The digital network is like a super highway,'' says Nick Morley, a Boston-based writer who covers ISDN for trade journals.
ISDN service is available in only a few cities, although trials and private ISDN exchanges are being set up nationwide.
In March, the Lockheed Missiles & Space Co. in Sunnyvale, Calif., used an ISDN system to transmit phone conversations, video for security cameras, as well as allowing desktop computers to access information stored on mainframes at opposite ends of the plant.
Within the next two years, students at the University of Michigan in Ann Arbor will be able to use ISDN to connect their home computers with the school's high-speed computer network, says Dory Leifer, a research programmer at the university.
`I TRULY believe that the small businesses and residential [offices] will benefit the most [from ISDN],'' says Richard Lush, director of ISDN marketing at Codex, which manufactures telecommunications systems. Mr. Lush says ISDN gives the small-scale telecommunications user ``the things that a large company has,'' such as access to high-speed, digital networks, without expensive equipment costs.
``That's not to say that the big industrial people aren't going to benefit,'' he adds.
Telephone analysts expect ISDN to cost no more than twice as much as conventional telephone service. The special ISDN telephones cost $500 or more, but prices are expected to drop as popularity increases.
Nevertheless, the digital features must still be turned on, which is often delayed as much by regulatory factors as by the technology, according to Joe Gustafson, director for ISDN product development at NYNEX.
``It's unfortunate that it's not available to the residence market,'' says Ron Hoffman, a communications specialist at the Massachusetts Institute of Technology, who is looking forward to the day he can connect his computer at home to his computer at MIT at ISDN-speeds.
Although MIT installed an ISDN telephone system in 1988, New England Telephone does not plan to offer residential ISDN service until 1991.
One of the last steps in computerizing the telephone system will be to replace the copper wire itself with glass, fiber-optic cables, which can carry a thousand times as much information. Fiber optics are already used for the majority of long-distance telephone calls in the US.
In some cities, fiber connects major office buildings directly to telephone company switches. Experimental trials presently taking place around the country are examining the feasibility of pulling the glass fibers directly to subscriber's homes.