JUDGE Harold H. Greene's order in the telephone case sets in motion the most extraordinary reorganization in the history of American industry. As a matter of law it is, no doubt, less important than the Supreme Court's decision in 1911 breaking up Standard Oil. But in its immediate impact on the economy, the effect of this order may well be greater. The American Telephone and Telegraph Company, a legal and nationwide monopoly most of its life, will now split off the local operating companies like C&P Telephone. It will proceed to turn itself into a profoundly different kind of company as it enters the hotly competitive computer and data processing businesses. These changes will ultimately affect nearly everyone who uses a phone.

Judge Greene's service to the public here has been incalculable. The original draft of the agreement, worked out between AT&T and the Justice Department last winter, left him in a peculiar position. With the arrival of the Reagan administration, the Justice Department had swung to a view excessively favorable to AT&T. It was left to the judge to restore a balance among the many contending interests. He has accomplished that work with great distinction, in the order that has now gone into effect.

But despite the happy outcome, it is difficult not to feel a degree of uneasiness at the degree of discretion that this procedure left to one judge. Not every judge would have responded so skillfully. Ideally, the issues here should have been guided by congressional legislation.

That did not happen because Congress was unable to pass a bill this summer. Questions had to be settled and, as frequently happens when Congress failed to act, the responsibility fell to the courts. Rep. Timothy Wirth's bill was beaten by the shrill campaign that AT&T ran against it, generating anxiety to the point of panic among some of the company's shareholders and employes. But it is also necessary to say that the congressional process itself contributed to the bill's collapse. To get the necessary majorities, Mr. Wirth kept having to write into it protections for more and more interests, making it more and more cumbersome and awkward.

It's a fair summary to say that the AT&T case followed the less desirable route, through the courts, to the more satisfactory outcome, in Judge Greene's order. When the order has been carried out, in a year and a half, Congress will have both the opportunity and the responsibility to return to this compelling subject and, if necessary, impose its own judgment on the direction that the new telecommunications industry is taking.