Inside Report (2)

What do Superman and at least one State Department official have in common? They both need to slip into a phone booth once in awhile.

New administration efforts to plug information ''leaks'' to the press appear to be having a chilling effect at the State Department. Some officials are reluctant to return calls to reporters. Others continue to talk but are more cautious than they once were. In some cases, they now carefully clear their remarks with superiors.

One congressional staff member says that an official whom he has long known has taken to calling him from pay telephone booths so that the official could guard against the call being overheard or tapped.