More American Households Installing Second Telephone Line : Telecommunications: Industry experts cite usage by baby boomer’s teen-age children, personal computers and the trend toward working at home.

“Get off the phone; I’m expecting a call,” is becoming a phrase of the past as more and more American households get second telephone lines to accommodate their kids and computers.

The boom, reflected in the 1994 results of the regional Bell operating companies, looks like an ongoing boost to industry revenue, analysts and executives said.

Local telephone companies said that most second home lines are ordered because teen-agers are hogging the existing phone or to give full rein to personal computers.

But it is also clear that more people are working from home, not only full-time at-home professionals but also those working outside the home who log on to computers in the evening for a few more hours of work.

“I absolutely, definitely see a continuing increase in second lines” to the home, said Karen Barnett, a product manager at SBC Communications Inc., formerly SouthWestern Bell.

“It’s going to get much faster,” Dave Goodtree, an industry analyst at consultants Forrester Research, said of the trend.

The reasons are simple: demographics, rising incomes, longer workdays and the falling cost and increased scope of telecommunications.

The baby boomers produced their own bulge in children, and many of them are now in their teens and demanding to use the phone more and more.

Middle-class incomes have far outstripped the real cost of telecommunications for the last 10 years, and now a whole range of new services and equipment is becoming affordable.

While telecommuting has yet to get a real grip on the way Americans work, the average workday is growing longer. Working from home in the evenings or on weekends is increasingly common, and much of that work is by either phone or computer.

Under the six-company regional Bell group and GTE Corp., about 5 million new access lines were added in 1994, bringing the U.S. total to 150 million.

A majority were for businesses, reflecting the economy’s improving strength, but a growing minority were additional home lines.

Detailed industry figures are sketchy, but in 1991 8.3% of NYNEX Corp.’s residential access lines were second lines. By the middle of 1994 this had risen to 10.1%.

BellSouth Corp. said that 1 million of its 20 million lines are second lines for homes, and 35% of these are listed as teen-agers’ lines.

The phone companies are overjoyed. SBC charges an average of $11.50 a month for a second line, compared with $20 to $30 for a first residential line.

But rental and flat-rate local revenue is peanuts compared with longer-term benefits. Every extra line means more medium- and long-distance calls, which are metered.

The Bells offer medium-distance (toll) calls, while for long-distance calls they reap hefty access charges to connect the customer.