The recent pledge by the American Telephone and Telegraph Co. to comply with President Carter's voluntary price guidelines is "at best illusory and, at worst, a deceitful trick," according to the director of a consumer group.

Samuel A. Simon, executive director of the National Citizens Committee for Broadcasting, a consumer group chaired by Ralph Nader, questioned the credibility of the AT&T pledge in light of its recent announcement of record earnings.

Simon called on President Carter and his chief inflation fighter Alfred Kahn to investigate the huge communications company and intervene with the Federal Communications Commission to force AT&T to reduce telephone prices to consumers.

"The promise not to increase prices in the face of apparently unlawfully high profits by a presumably regulated monopoly is an outrage and an affront to President Carter and the people of this country," Nader said yesterday.

Jay Soloman, head of the General Services Administration, has called for a reduction in telephone prices that would save consumers $600 million.

In a letter to President Carter, NCCB's Simon pointed out that AT&T has increased earnings 18 percent over the same quarter last year.

"[To] thoe of us asked to stick to 7 percent (not 18 percent) increases," Simon said, "it seems that an outright price reduction by AT&T is in order, not merely a continuation of the ever increasing monopoly profits."