Attorneys for American Telephone & Telegraph Co. attempted today to discredit testimony by MCI Communications Corp. Chairman William McGowan and alleged that McGowan had misled a jury here as to MCI's intentions to enter the long-distance telephone business in the early 1970s.

The AT&T attorneys suggested that McGowan and his company have little legal foundation to their claim that they were denied access to Bell System telephone lines that MCI claims it was entitled to under a 1971 decision by the Federal Communications Commission.

George L. Sauders, a Chicago attorney representing AT&T, cited a McGowan speech in August 1972 in which McGowan said that basic telephone service "is and should remain a natural monopoly."

McGowan said the remarks before an association of Midwest regulatory utility commissioners were designed to convince the state officials that the 1971 FCC decision didn't mean that their "comfortable world" of state regulation was coming to an end.

"In a word," Saunders interjected, "you weren't telling the truth."

McGowan then said that in light of the growth of AT&T competitors, his 1972 remark "does not reflect my thinking as of 1980." U.S. District Court Judge John F. Grady, who initially wanted to prevent the reading of the McGowan speech, permitted it after attempts to paraphrase the remarks appeared impossible.

Saunders' questioning at that point and during subsequent interchanges indicated that AT&T is attempting to convince the jury here that MCI and McGowan, the chairman and executive responsible for the growth of the Washington-based firm, had misled the FCC and others in its proposals to enter only the specialized telephone business.

The testimony came during the fourth day of the trail of MCI's antitrust suit against AT&T. MCI is seeking triple damages of $900 million, charging that AT&T illegally prevented it from obtaining access to telephone facilities vital to its growth during the early 1970s.

Saunders was attempting to show in his interrogation of McGowan that McGowan had taken the FCC's so-called "specialized common carrier" decision of 1971 to mean that MCI was free to insist on a broad range of telephone services, some of which were in direct competition with AT&T.

McGowan was questioned initially by MCI lawyers for about two hours and 40 minutes. He told the jury then that MCI had attracted investment funds from banks and other sources under the premise that it would be able to purchase a variety of telephone interconnections from AT&T and its Bell System subsidiaries.

MCI introduced a deposition from former AT&T chairman John deButts in which deButts said that the "only way they (MCI) could serve their customers is the local distribution facilities," referring to Bell System hookups.

McGowan painted a picture of AT&T which suggested that the world's largest company had blocked MCI's effort to contract for the local Bell links to its own business telephone services.