Ma Bell cuts the apron strings

If bells are ringing in telephone company front offices these days, it is not hard to understand why. In signing the consent decree between the US Justice Department and the American Telephone and Telegraph Company this week, US District Judge Harold Greene has given the go-ahead to a plan that will see the 22 local Bell subsidiaries split off from Ma Bell sometime during the next 18 months. The divestiture (involving two-thirds of AT&T's $138 billion in assets) will constitute the most significant restructuring of a basic industry in the US since the historic antitrust cases of the early years of this century.

Granted, Judge Greene's consent decree accepts the basic framework of the original January settlement between AT&T and the government. But, at the same time, Judge Greene revised the agreement in sensible ways that had been sought by both consumer groups and backers of the local Bell systems.

For instance, Ma Bell will be restricted from offering its own information and news services in competition with newspapers, although it will be able to transmit such services provided by information firms. Rep. Timothy Wirth, chairman of the House telecommunications subcommittee, is certainly correct in calling the provision ''a ringing endorsement of the First Amendment, and of the importance of diversity of information.''

In addition, the revised plan allows local Bell systems to issue business directories and market telephone equipment. Both steps had been denied local companies under the original settlement. The effect should be to help offset the costs of providing local telephone services.

One era in telephone service in the US is about to end.

Ma Bell, and the local Bell systems, deserve the praise of all Americans for having provided what is probably the finest telephone service in the world.

As a new era in telecommunications begins, there is no reason why that track record cannot continue.