LAST YEAR Colleen Foley, 22, of Naples, Fla., was working at her mother's flying school and considering going to school to become a journalist.

Then, watching television in July of last year, Foley saw an advertisement from the Cambridge, Mass.-based organization, that urged her to "Reach for the Power. Teach!" As a result, Foley, who had never considered being a teacher, has enrolled in an associate of arts program at Edison Community College in Naples and intends to go on to earn a bachelor's degree so that she can become an English teacher.

"The ad and brochure changed my mind," Foley says, "by waking me up to the sides of teaching I wasn't looking at. I have a hard time being in front of people. But I got up the other day in public speaking class and told them all about Recruiting New Teachers, about this whole program."

RNT, Foley said, has "given me the confidence to feel my efforts will be worthwhile. They changed my mind."

The nonprofit service called Recruiting New Teachers works this way. Someone sees an ad on television or in print and calls the toll-free number. A taped voice requests and records the caller's name and address. The caller then is mailed a questionnaire that asks for more detailed educational, career and personal information. RNT sends this data to one or more of 370 cooperating organizations, which then contact the caller.

For example, 45 "Teachers of the Year" throughout the country contacted respondents in their areas with information on teaching as a profession. The Council for Exceptional Children, which serves handicapped and gifted children, has done the same for 4,500 respondents who indicated interest in special education or in teaching English as a Second Language.

The second largest school district in the nation, the Los Angeles Unified School District, sent several thousand respondents invitations to a job fair last summer. Teachers College of Columbia University in New York has established an RNT data base and has sent information about the college's education graduate school to 15,000 respondents. Eastern Montana College's Department of Education has contacted respondents who are potential teachers for the state's network of 115 rural one-room schoolhouses. The New York Hall of Science has informed respondents about its scholarship program that combines studies at Queens College with part-time work at the museum.

RNT began five years ago as a project of the National Association of Independent Schools, a clearinghouse based in Boston and in Washington, D.C., for non-public schools. As NAIS President John C. Este Jr. explains, some members of the organization's board were "curious that no one was paying attention to the U.S.'s impending teacher shortage."

According to the Department of Education's National Center for Education Statistics, the U.S. will need at least 2 million teachers over the next decade because of growing student enrollments and the anticipated retirement of many who are now teaching. There are already shortages in rural and inner city districts, from Appalachia to Miami's Dade County.

The NAIS board asked Este to form a committee that would do something about the impending shortage. Although RNT was Este's idea, one of the first people he approached was philanthropist and education advocate David Rockefeller Jr. Este says today, "He's the one who made it soar. He's been terrifically helpful."

The first ad encouraging would-be teachers to call the toll-free number aired nationally in April 1988. "The calls were just pouring in," said David Haselkorn, executive director of RNT. "It caught us all by surprise."

"We were given to believe that 50,000 would respond and we got 190,000" in a year's time, says David Rockefeller. (By now, the number has surpassed 370,000.) Thirty-one percent of the callers have have been black, Asian and Hispanic, and 60 percent -- again to the surprise of organizers -- have been mid-career.

Haselkorn said he believes that many of those in mid-career are people who "went into fast-track jobs that may not provide the gratification" they want. "I would hope that this signals a gyroscopic correction of the American psyche, a move against the culture of narcissism, of looking out for Number One," he said.

Since 1986, RNT, with Rockefeller's assistance, has raised $2.3 million, which includes grants from foundations and corporations. Some $55 million in advertising has been donated by Madison Avenue firms. The first ad has been followed by a second featuring Edward James Olmos, star of "Stand and Deliver," the acclaimed film about Jaime Escalante, the high school math teacher whose inner-city students' scores on the Advanced Placement calculus exam have exceeded anyone's expectations. There is also a poster campaign designed to get high school students to consider a teaching career. It will reach schools across the United States, including those in Washington, D.C.

Colleen Foley, in the associates degree program at Edison Community College, like others across the nation, is content and productive, on the trail to becoming a teacher.

"Before, I wasn't excited about my future. Now, because of the changes I can make -- even if I can only affect one in the group -- I can serve to change the future. I feel like these people {RNT} did that for me, and I want to give that back," Foley said.

Another respondent, 22-year-old Dean Fusto had attended several colleges and tried different majors before graduating from the University of North Florida in Jacksonville with a bachelor's degree in Spanish. While traveling to visit relatives in New England about a year ago, he stopped in a hotel in North Carolina, saw an RNT ad and placed the call. Fusto is now enrolled at the Experiment in International Living in Brattleboro, Vt., one of the senior international exchange programs in the country, where he is studying to teach English to foreign students abroad.

"Before," he says, "teacher certification was a fuzzy picture. Here . . . this is exactly what I was looking for. This Vermont school was a real find. I'm really enjoying the program. Student teaching is really great."

For George Sanders, RNT rekindled his teaching career. Sanders, who is 34, had been teaching in a San Antonio, Texas, parochial school, when he was forced to leave because of budget cutbacks. Two years ago, discouraged, he saw the RNT ad. He called and received information from school districts in Phoenix, Las Vegas, Palm Springs, Oklahoma and Denver.

A Phoenix school official invited him to interview for a high school teaching position.

"There's no doubt that RNT was responsible for that letter," says Sanders, who now teaches English to 10th, 11th and 12th graders at North High in Phoenix. "It's meant a future."

Barbara Hall is a free-lance writer who lives in Brooklyn, N.Y.