U.S. District Court Judge Harold H. Greene formally took control of the Justice Department's landmark agreement with American Telephone & Telegraph Co. yesterday. He immediately voided an earlier decision by another federal judge that let the settlement go into affect only four days after it was signed earlier this month without any public hearing.

In other developments yesterday:

* The Federal Communications Commission gave AT&T and 11 other large interstate telephone companies permission to greatly accelerate the depreciation of their equipment and facilities. The unanimous approval of a long-pending matter should lead to more rate increases in local and long-distance telephone bills.

* AT&T began taking steps to implement what it calls "the most significant change in the Bell System's long history" by announcing major organizational changes to help prepare the communications giant for the break-up.

Greene said he would not accept the AT&T-Justice settlement or drop the government's eight-year-old antitrust suit against the company until he holds hearings to see if the consent decree promoted competition and is in the public interest. The judge also set up a detailed schedule to give all interested parties a chance to comment.

Under Greene's plan, it will be three months at the earliest before the judge approves the consent decree, which calls for AT&T to divest itself of about two-thirds of its assets by spinning off all local operations of its 22 regional subsidiaries.

Concerns that the settlement could lead to sharply higher local rates is expected to be one of chief issues explored in Greene's hearings. Even though Justice and AT&T contend the settlement will not in itself lead to higher rates, key congressional leaders and state regulatory commissioners have already lodged public complaints about the settlement, saying they fear it could raise local rates, especially those for rural customers.

It was partly that concern that led the National Citizens Committee for Broadcasting to announce yesterday that it will ask Greene not to approve the consent decree. This is the first group to announce it intended to fight the substance of the decree.

Up to now, most groups have complained that with the earlier approval of the settlement by another federal judge, they were precluded from commenting on it as they were entitled under a law that requires public review of settlements in antitrust cases.

For that reason, Greene had refused to dismiss the government's antitrust case--which the settlement was drawn up to end.

Under Greene's order yesterday, the government must publish within 15 days the terms of the agreement and the reasons why the government accepted it. The public will then have 60 days to comment and the government another 15 days to reply. Greene said he may also hold hearings on the settlement or appoint experts to examine it.

Although Greene's order delays the divestiture plan for some time, AT&T officials said they were pleased by his decision to publicly air the concerns. "We will cooperate fully with the court," said AT&T spokesman Pic Wagner.

Meanwhile, beginning Feb. 1, the top management of AT&T will be reorganized to begin preparing for the divestiture required by the consent decree.

Chairman Charles L. Brown and three other senior AT&T officers-- William M. Ellinghaus and Vice Chairmen William S. Cashel Jr. and James E. Olson--will work as a group on corporate strategy, resource allocation and other critical issues. Cashel and Howard J. Trienens, vice president and general counsel who served as AT&T's chief architect in the agreement with Justice, will have direct responsibility for planning the corporate divestiture.

Day-to-day responsibility over AT&T's general department will be divided among five executive vice presidents, with Thomas E. Bolger, a former president of Chesapeake & Potomac Telephone Co., responsible for designing and supervising the prospective centralized staff for divested companies.

Charles E. Hugel will continue to oversee AT&T's interest in the Western Electric Co. and will assume the same role with Bell Telephone Laboratories as well as a new subsidiary, AT&T International. Charles Marshall, a newly elected executive vice president, will take charge of a new subsidiary AT&T is creating, called "Baby Bell" in communications circles, which will offer telephone equipment and sophisticated computer services.

Morris Tannenbaum will assume responsibility for design and supervision of AT&T's future intercity long-distance network and Kenneth J. Whalen will continue responsibility over regulatory matters, tariffs and costs and will also be responsible for public affairs, human resources and labor relations.

The FCC staff estimated yesterday that faster depreciation schedules approved will entitle telephone companies to collect about $1 billion more in revenue from the FCC and state regulatory commissions. However, AT&T officials noted that the change was already anticipated by the FCC and some state regulatory commissions.