The landmark hearings before Judge Harold H. Greene examining the future shape of the telephone industry concluded yesterday with a wide-ranging debate over how to meet what one lawyer called "the opportunity to usher into existence the American information age."

Following two days of sometimes contentious questioning by the judge of the Justice Department's antitrust policies past and present, Greene shifted his attention to the question of whether antitrust rules are depriving the public of high-technology products that might be provided through the local telephone system.

At present, the regional phone companies, including Bell Atlantic, which serves the Washington area, are prohibited by the consent decree governing AT&T's breakup from offering their customers information services, from simple voice storage service to electronic publishing.

The regional companies are urging Greene to lift that restriction and others barring them from providing long-distance service and manufacturing telephone equipment. At hearings Monday and Tuesday, which focused on long distance and manufacturing, Greene expressed sharp skepticism about whether the regionals could compete freely without violating antitrust laws.

The judge conceded yesterday, however, that the information services issue was different and "probably is the most difficult of all the ones we have."

Those supporting the regionals in their request to lift the information services prohibition, including the Justice Department, argue that only through the economies of scale present in the local telephone network can the full benefits of new technologies be made available to all consumers at a reasonable cost.

"We say the scale tips in favor of {lifting the restriction} and that's because, for the first time, information services would be made available at a price the average person could afford," argued David I. Shapiro, an attorney representing the regionals. Shapiro said that if the restriction were eliminated, the regional companies would soon offer all consumers a variety of directory, advertising, and other information services through inexpensive computer terminals installed in homes.

Such a system, called Teletel, is already established in France, subsidized by the national government.

Bell Atlantic spokesman Pete Hoffman said yesterday that Bell Atlantic would "probably" be interested in providing a wide range of information services, but only if a true demand for the services exists. The company has done no market research studies on the issue.

C&P Telephone Cos. President Thomas Gibbons has drawn up a list of services the telephone company would like to provide. The services include voice storage and retrieval, similar to answering machines but provided inside the phone network; electronic document services for businesses to facilitate ordering, invoicing, and billing; remote utility meter-reading; news and entertainment data-base services for home and business users, and electronic white and yellow page directories. C&P officials argue the company needs to expand into these new markets in order to support universal telephone service.

Bell Atlantic's Hoffman said that the company has virtually no competitors for many of these services because vendors would have to locate equipment at some distance from the telephone company, adding to the cost. Under new federal rules, the regional companies are supposed to submit plans for how competitors would hook into their networks to provide many new services.

Bell Atlantic's plan has come under severe attack for proposing to charge competitors about five times more than it would charge itself for telephone lines to provide the services. "Everybody jumped on that one and beat us up like crazy," Hoffman said. The company argues it costs more to extend the lines to vendors. But, in response to the pressure, Bell Atlantic changed the proposal so that costs for both Bell Atlantic and competitors would be equal.

Greene must decide whether lifting the information services restriction would create a "substantial possibility" that the regional companies could use their control over the local telephone network to impede competition. But the judge has indicated that he may consider public interest arguments in the information services area in addition to applying legal antitrust standards.

Consumer groups are divided on the issue. Samuel A. Simon, speaking for the National Consumers League and other groups, said that information services was one area "where the court's initial model has not worked." But James Blaszak, who represents the Consumer Federation of America, among others, argued that "the bottleneck still exists" and that the regionals would impede competition if they were unleashed.

Greene, who is expected to rule before the end of the year, concluded the hearings by acknowledging that his decision would be difficult. "All I can say is, I'll do the best I can," he said.