The most profound legislative restructuring ever undertaken affecting a sector of U.S. business is at a critical stage as Congress prepares to make a final decision on how to deal with the nation's antiquated communications laws.

Supporters of the effort, including the Carter administration, say legislation is vital to both to the burgeoning communictions industry and the national economy.

Opponents of the effects in both the House and the Senate disagree. They say that the legislation to restructure the industry as a whole as well as the nation's largest communications corporation, American Telephone & Telegraph Co., would do the opposite, arguing that enactment of the bill would stifle competition in the communications world.

But if last week's effect by the House Commerce Committee to pass a telecommunications bill are any indication, most of the 43 members of the panel really do not seem to recognize what may be at stake.

"Congress is bearing down on regulatory agencies, taking the position that they should be making policy," says one top federal policy maker. "Now you have Congress purporting to write very significant and complex legislation and you just don't sense there will be any informed debate on these subjects."

The debate over the bill is, by congressional standards, odd in a number of ways. Most of the time, Congress reacts to existing problems rather than to what the future holds. Organized single-interest groups usually dominate the debate. But this situation is different since interests are diverse, positions can fluctuate and problems are more long-range than short-term.

For example, the International Communications Association, which represents more than 450 large companies that do more than $1 million a year in communications business, had -- cautiously and under political pressure -- agreed this spring to be part of a coalition supporting legislation.

Citing "an unfortunate number of draftsmanship errors," the prestigous group -- headed by Robert Bennis of Westinghouse Electric Corp. -- this week asked Congress to delay the legislation until next session.

Suddenly, the National Retail Merchants Association, a trade group representing 35,000 stores with sales of close to $100 billion, this week endorsed a similar position, saying the bill requires further hearings.

It is no wonder then that Congress has a tough time with the issues. The House Commerce Committee made virtually no progress this week in a short mark-up session that turned into a procedural tiff and ultimately became merely a reading of the bill. Another session is expected this week.

But with a recess for the Democratic convention approaching, most observers feel that without House committee passage of the bill this week, the legislation is dead.

"We've got to get this out before the next break, or I'll probably give up," says Rep. Lionel Van Deerlin (D-Calif.), chairman of the House communications subcommittee.

Passed easily by the House communications subcommittee earlier this year, the legislation would among other things:

Deregulate the manufacture and sale of telephone receivers, other instruments and intercity telephone services and block regulation of data processing and other communications equipment.

LIFT AT&T's 1956 consent decree with the government that bans Bell System companies from participating in unregulated communications fields and require AT&T to set up a fully separated subsidiary offering these services. A 10-year period for the restructuring at AT&T would also be set up.

Establish an access fee plan for telephone companies hooking into the Bell telephone system.

On the Senate side, provisions that would permit the Federal Communications Commission to keep a closer watch on the evolution of the Bell System into an unregulated marketplace, have caused a bitter fight between the sponsors of the legislation and the Bell System. AT&T wants committee action on the controversial issues, recognizing that with subsidiaries in every con congressional district, the phone company has some votes.

"We are anxious for some meaningful legislation in this session of Congress," said an AT&T spokesman. "Let the members decide the issues. Any place where there is controversy or differences of opinion, it would be just as well to let them vote on it."

The Senate bill has its own unique political troubles, since it, unlike the House version, include highly controversial provisions dealing with the broadcasting industry.

But Sen. Minority member of the Commerce Committee and a sponsor of the bill, says he is ready to support an effort to move the Senate legislation closer to the House version, which sets a restructing plan that essentially cannot be altered by the FCC.

Packwood admits, however, that since the Senate process broke down last month, little has been done to bring the legislation back to life. "If the Senate doesn't act by Labor Day, there will be no bill," Packwood said. t

So, while there is little happening on the Senate side at this point, the communications action has returned to the House, where Van Deerlin, who fathered the legislative effort four years ago, has run into some serious problems.

One of Van Deerlin's most serious challenges has come from a colleague, Rep. Peter Rodino (D-N.J.), chairman of the Judiciary Committee, who last week asked that the whole effort to restructure AT&T be abandoned until the Justice Department completes its landmark suit seeking to break up the Bell System. Implicit in Rodino's request is the threat that he would seek and receive jurisdiction over any bill the full Commerce Committee passes, a move that could kill the entire effort.

Rodino argues that if Congress revamps AT&T's structure, the antitrust court may have legal troubles ordering such a remedy, and Van Deerlin says he knows of Rodino's power. "If it comes to clout, I can't stand up to Rodino," Van Deerlin said. "But there is a need for structural reform which can be accomplished without waiting years for the courts."

But another difficulty, which Van Deerlin and another key House supporter, Rep. Timothy Wirth (D-Colo.), may have solved Friday has come from the American Newspaper Publishers Asociation, which has been aggressively making the case that an unleashed AT&T could use its virtual monopoly over home telephone service to become an originator and distributor of news and advertising.

The ANPA has suggested that the bill be modified to preclude AT&T from getting into such ventures. After negotiations, Van Deerlin and Wirth have agreed to support an ANPA-endorsed amendment to limit the Bell System mass media role.

In a letter sent Friday to other House members, Van Deerlin and Wirth said that Wirth would offer an amendment this week "which will clearly prevent AT&T from controlling information content, arrangement or delivery, whether AT&T originates the information or places the information of others in a data retrieval system."

Under the legislation, however, AT&T could offer the facilities for information services, including computer capacity and transmission equipment, if those facilities are offered to all users under the same terms.

And yet another roadlock may have come from the Carter administration, which recently has proposed major revisions in the legislation already adopted by the subcommittee.

Some congressional members have reacted bitterly to a recent letter from the Department of Commerce, recommending significant changes in the bill this late in the process.

But at this point the administration has influence over only a handful of Commerce Committee members. "There are far more important forces at work than us," admits Henry Geller, head of NTIA.