The technological explosion that blew away the Bell System's telephone monopoly also has unearthed a long-buried federal bureau.

The resurrected agency is the Common Carrier Bureau of the Federal Communications Commission, which has jurisdiction over interstate telephone and radio communications.

It used to seem that the public only heard from the bureau when the commission acted on matters affecting the American Telephone & Telegraph Co. In the interim, the bureau said little and appeared to do less.

But rapid technological growth, pushed by aggressive new companies, has changed all of that. AT&T started getting competitors and antitrust suits, and the Common Carrier Bureau started getting work.

The turnabout has put the 300-person bureau on corporate "must-see" lists. AT&T is stopping there on its way to divestiture. Satellite communications companies are stopping by on their way to outer space. It is heady stuff, bureau chief Gary Epstein admits.

"I know that people used to regard this as something of a burial ground," he said. "But no one can say that today. What's going on here now is very exciting."

The bureau is strategically placed to shape a major part of the so-called "information age." It does the groundwork for the commission's decisions on telephone rates, telephone and radio communications licenses and on the use of emerging technologies, such as cellular radio. It also processes applications for international cable operations.

The bureau is reviewing an estimated 20,600 applications from companies seeking a share of the growing telecommunications pie. And the applications reflect the growing diversity of the domestic telecommunications industry. There are 7,000 applications for microwave transmission systems, 3,000 for satellite communications plans, 10,000 for land-mobile radio operations and 600 for cellular radio licenses.

AT&T already has created an unregulated telephone equipment company, American Bell, and it plans to spin off its operating companies into seven regional units. All of that means exchanging licenses and other assets between AT&T and the soon-to-be-independent operating companies, setting up new rate structures and establishing new rules for supplying telephones and related equipment to consumers.

The commission last week asked AT&T to submit detailed plans for exchanging nearly 2,000 radio licenses and other assets under FCC jurisdiction that are affected by the divestiture order.

Common Carrier Bureau employes, as a result, are bracing themselves for a deluge of paper. The first wave should hit March 1, the FCC's first deadline for an AT&T response. More paper, in the form of "supplemental information," is scheduled to arrive by July 1.