More than 140,000 investors in the District, Maryland and Virginia last week received an annual report from the largest company and biggest private employer on earth.

They are among the 3 million stockholders of American Telephone & Telegraph Co., and most of them also are residential customers of the firm, through AT&T's wholly owned Chesapeake & Potomac Telephone Companies.

At their work in private industry or government, a few of these investors also may be familiar with a new breed of telephone services from companies that are seeking a share of a business long dominated by Mother Bell.

And, if the investors studied their AT&T reports carefully, they discovered a most unusual document that directly confronts the new competitive environment in which their company competes.

Inserted in the middle of 36 pages is a 4-page "statement of policy," a detailed account of the Bell Systems's goals, responsibilities to its many publics, an assessment of private enterprise and the necessity to earn profits and a commitment to "be good citizens in the communities we serve."

An outsider might assume that such a non-financial accounting of a corporation's view of itself belongs in any annual report, but such a statement is rare. Investors interested primarily in dividend yields and stock prices may find little to recommend in the four pages of type.

But to John D. deButts, the 62-year-old chairman of the telephone company, the annual report statement "is the first time ever that our policy has been pulled together in one place."

Various elements of Bell System policy and philosophy of business have been in place for decades and have not been changed, said deButts. A native of Greensboro, N.C., and a graduate of Virginia Military Institute, he began his AT&T career in Richmond for C&P as a $100-a-week management trainee.

A "key part" of the policy statement is a goal that dates from 1927, providing a guide to all men who since have become chief executive of one the world's most powerful institutions, the telephone company. In an interview, deButts restated it thus: "The best possible service at the lowest possible cost, consistent with financial stability."

And who could argue with that?

The answer is that many people do contest deButts, arguing that such phrases act as shields behind which the status quo of monopoly can be maintained for AT&T. One, for example, is Washington lawyer John M. Eger, former head of the White House Office of Telecommunications Policy.

AT&T is at the center of a furious storm over the future of American telecommunications policy and Eger has contended that the Bell System - in particular, deButts, whom Eger describes as "astute" - misstates the main issues which this nation faces about the future of its largest business enterprise.

As Eger summarizes deButts, the AT&T chairman doesn't think competition will work. "Our dilemma is that too many Americans - in and out of Congress - are ready to believe he's right.Why? Because AT&T rests on the laurel of having given us the 'finest telephone service in the world'," Eger told the City Club of Chicago last November.

"And too many Americans are not yet aware that this fight over competition isn't really about telephone service at all. It is about the future of computers and communications in the information age; and it is about freedom in the marketplace," he said.

The AT&T philosophy of universal service at reasonable rates, restated in the new annual report, also was the goal of government when regulation was substituted for competition and the Bell System was given a virtual monopoly to build a national telephone network.

But in a new era of swift technological change, the burdens and benefits of regulation have shifted to the advantage of the monopoly at the potential expense of consumers, according to Eger and other AT&T critics.

The Federal Communications Commission, with an original role of protecting consumers against a necessary and government-protected monopoly, "has now been placed in the ridiculous posture in our free-market society of 'permitting' competition," said Eger. "And what that means is that any man or woman who comes up with a better communications mousetrap has to ask the government for permission to go into business and compete with Bell."

It is in the wake of such attacks on AT&T that a full statement of policy has been printed. Apparently, deButts is expanding his game of "hard ball" with government and competitor critics, seeking to build support for his program from among the Bell System's stockholders after failing to convince Congress that legislation should be enacted to control competition.

AT&T did ignite something on Capitol Hill when it joined with other firms in the telephone industry (with which it shares Bell System long-distance revenues) to propose a bill designed to curb the potentail loss of high-profit business while leaving behind a mandate to continue less profitable operations. What has been started, however, is a thorough review of the entire Communications Act.

According to deButts, AT&T "accomplished what we wanted, we got attention."

"I tried to get the public to understand" that they could be "hurt in a competitive arena," he said. The goal was to "stop for awhile" and assess the impact of recent FCC decisions opening up various business sectors for competition. Although deButts got attention for the so-called Bell bill, he conceded that there has been "no halt" in the expansion of competition for his firm.

"We recognize, however, that we are not the final arbiters of the public interest. That is why over recent years we have undertaken to speak out for policies we believe will help service and against those that might impair it. This we will continue to do. For only as we are ready to speak out what we believe and to test our convictions against the convictions of others can we do our part in assuring that what is declared to be the Public interest actually is!"

That's a section of AT&T's new policy statement and it clearly reflects the views of deButts. Other points emphasized include:

A "first responsibility" is service to the public. "Only so long as we maintain a competent and well-motivated work force can we serve well. Only so long as we achieve good earnings can we attract the capital necessary to maintain good service and to enhance our ability to serve better."

"Now that just about every U.S. home and business has a telephone, some say (the) goal (of universal service) has been achieved. We don't. We remain a long way from achieving the universality of communications in our society that our technology can accomplish."

"Competition for competition's sake is not our aim. Only so long as the services we offer in competition with the services of others produce revenues over and above the costs of providing them - or regulators determine that there are overriding public-interest reasons for doing so - are we warranted in continuing in the marketplace."

To the degree that competition forces AT&T to relate actual costs of some services to rates, local telephone charges will rise and jeopardize a policy under which residential service rates have been kept lower through higher profits from business services now sought by competitors. "In no instance, we believe, should regulators require us to set higher rates simply to protect competitors or preserve 'competition'."

As chief executive of a business enterprise with annual revenues that surpass the gross national product of most countries around the globe (AT&T in 1977, $37.06 billion; Egypt in 1975, $11.4 billion), deButts could be expected to be a man on the spot at almost any time. AT&T's operations are just too extensive, its impact on the economy so great, that any person who sits behind the main desk of the headquarters office at 195 Broadway in Manhattan is certain to be a focus of attention on many issues.

But for deButts, who will complete six years as AT&T chairman on April 1, there has been controversy as well as attention. Many of the 360 addresses he has given as head of the Bell System have focused on controversy, particularly the threat of competition. He has brought a new, aggressive style to leadership of AT&T and even appears regularly in television and print commercials, stating again and again his basic warning that his company should not be ripped apart by competition or government trustbusters.

"I take it a month at a time," said the man whose company is the subject of a major federal antitrust case seeking to split the firm's telephone service from research and manufacturing subsidiaries, of 40 private antitrust cases, of bitter allegations about the use, of AT&T muscle in the marketplace to thwart competition that is legal.

The AT&T chief denied that there has been any basic disagreement among top executives or AT&T's board members about the strong, defensive posture he has developed. DeButts also said he expects to remain at the healm of the company until age forces retirement on April 10, 1980, a clear indication that his policies will remain intact. In 1977, he was paid $571,763.

In addition to an outline of policies in the AT&T annual report, deButts said that last year his company's management wrote a five-year plan, for the first time, to guide decisions and measure performance in an era during which the biggest change will be in technology. Now he has subordinates working on AT&T's first ten-year plan.

According to deButts, his company's biggest problem is the adverse impact on its "ability to provide service" from competition, from government regulations and from government itself in an antitrust case the business executive said may cost $1 billion and will still be in court on his day of retirement.

Just as he expressed unhappiness about the battle between the Justice Department and his lawyers, deButts also said there is "too much contention" in the country today. He called on more business leaders to support programs of President Carter they can stand behind, and he expressed confidence in the economy, noting an accelerated growth rate in long-distance calls as an indicator.

As for the annual report, its production figures befit a company that is assessed by superlatives, one that earns more than $1 billion of profits every three months. About 4.1 million copies were printed for distribution to stockholders and the firm's nearly 1 million workers.

Mailing of the report and proxy statement for AT&T's annual meeting on April 19 in Miami Beach took two weeks. If piled up, the reports would be taller than both World Trade Center towers in New York; they weighed 1 1/2 million pounds.