Former American Telephone & Telegraph Co. chairman John deButts said yesterday that during his critical seven years as chief executive of AT&T the company met the requirements of communications laws but rarely paid attention to the antitrust consequence of Bell System actions.

DeButt, who was chairman of AT&T from 1972 until 1979, repeatedly stressed that actions taken by the company in the late 1960s and early 1970s in response to the emerging competitive communications market were designed to ensure the maintenance of the nation's telephone network. DeButts testified in the Justice Department's antitrust suit against AT&T as a defense witness.

At one point during deButts' daylong testimony, Gerald Connell, head of the Justice Department's AT&T trial team, asked the former AT&T chairman whether the obligations of the antitrust laws compelled the company to take steps beyond those ordered by the Federal Communications Commission.

"No I didn't know that," deButts said. "If we followed the regulations . . . that's what we were required to do. I don't recall anybody telling me to go beyond what the FCC said."

The Justice Department is seeking in its seven-year-old suit to break up AT&T -- the world's largest company -- became of alleged violations of antitrust law. Much of the government's case is based on the government's case is based on events that occurred during deButts tenure as AT&T chaiman.

DeButts' testimony, which is considered vital to AT&T continuing defense in the suit, stressed the decisions the company made to respond to competition. The 66-year-old resident of Upperville, Va., defended decisions made during his tenure to challenge the extent to which telephone equipment manufacturers and long-distance carriers could connect their products and services with the AT&T network

DeButts said that in 1973, after the key FCC decisions, he did not seek to block competition, but sought only to ensure that "expansion and experimentation be held up" until the FCC studied "the long-term impact" of increased competition on all AT&T customers.

He explained that the company's concerns were with the so-called "harms" to the network that the hookup of non-AT&T staff studies of such dangers were "inadequate."

In written testimony, deButts likened the question of damage to the network to that which would face scientists "who had expert knowledge of the risks posed to the earth ozone layer by certain aerosol propellants, but no empirical evidence that the atmosphere was, in fact, deteriorating."

In addition, deButts said that under his aegis the company was concerned with "creamskimming" by competing long-distance carriers, who were siphoning business from AT&T's profitable long-distance routes.

In his written testimony, deButts said the "inevitable result" of competition would be "an increase in the rates which existing carriers would have to charge" for residential service.

DeButts wrote that he "grew up" in the Bell System believing in the company's "obligation" to serve "all the people" and to maintain the ability to provide that service. "The decisions I made represented my best efforts to comply with new obligations without sacrificing these older but sound premises," he said.

"Notwithstanding this lawsuit, in which the government has found fault with my decisions, and notwithstanding the spate of private actions which have arisen out of these decisions I do not in good conscience believe I could have done otherwise than I did," he concluded.