A House communications subcommittee yesterday took a significant step toward cutting the regulation of the telecommunications industry, overwhelmingly approving proposals to alter the structure of the Bell Telephone System.

The bill's supporters emphasize that the legislation is designed to free the growing telephone industry from regulation and should not alter the Justice Department's antitrust case against American Telephone & Telegraph co.

On the other hand, the bill's opponents, including some computer and telecommunications industry companies and associations and several consumer activist groups, charged that the amendments to the Communications Act will effectively encourage the growth of the Bell System and could hamper the antitrust case.

"The bill still goes too far too fast," said Howard Symons of Congress Watch. Referring to AT&T, Symons said the proposals "allow an 800 pound gorilla to sit whereever it wants to."

The bill emerged yesterday from the House Commerce communications subcommittee, which has been working to rewrite the Communications Act for more than three years.

The bill's most diligent proponents, Rep. Lionel Van Deerlin (D-Cal.), the subcommittee's chairman and Rep. Timothy Wirth (D-Colo.), who engineered vital revisions of Van Deerlin's most recent bill, hailed its passage.

But Wirth, echoing the views of a number of panel members, said in an interview that the bill is far from perfect.

"While this is far from a perfect piece of legislation and there could be stronger protection for consumers, we ended up with the best possible bill," Wirth said. "On a 10-point scale, this is a seven or seven and a half."

In essence, the bill frees the Bell System from a set of constraints on its operations, and lifts the 1956 consent decree which limits AT&T's ability to enter into a series of competitive communications markets.

But is also calls for a restructuring of the telephone giant, forcing At&t to set up separate subsidiaries in order to compete in unregulated tele-communications fields. Among measures added to the package yesterday was an amendment to strengthen the ability of the Federal Communications Commission to step in if AT&T violates the separate subsidiary provisions.

In addition, the package calls for the deregulation of a variety of services, including the manufacture and sale of receivers, switchboards and other equipment.

It also provides a set of proposals designed to prevent discrimination against rural phone service customers and companies. Those proposals, submitted by Rep. Albert Gore (D.-Tenn.), won unanimous subcommittee approval yesterday.

The entire package, which was passed by the subcommittee by a 13-1 vote, now goes to the full House Interstate and Foreign Commerce Committee. Van Deerlin said he expected the full committee to take up the bill next month.

AT&T Vice Chairman James E. Olson praised the bill in December when it was introduced, calling it the best piece of telecommunications legislation to be produced thus far by Congress."

But the Carter administration, which has encouraged the subcommittee to consider the legislation promptly, is considering the bill, now that the sub-committee work is complete. Administration officials have not endorsed a specific piece of telecommunications legislation.

Meanwhile, Sen. Ernest Hollings, (D.-S.C.), chairman of a Senate communications subcommittee, yesterday gave a speech on the issue and said a new version of Senate communications legislation would be introduced soon and he hopes the bill will be approved by his panel this spring.