National Public Radio, accelerating its move into private enterprise, announced yesterday that it will join a Mississippi firm in establishing a nationwide radio paging system that will allow subscribers to be reached on their beepers anywhere in the country.

If awarded a license by the Federal Communications Commission, NPR and Mobile Communications Corp. of America will establish a new firm to be known as National Satellite Paging Inc.

From a control center in Washington, the paging company will use NPR's existing satellite links to transmit paging messages on the new frequency recently earmarked for that purpose by the FCC. Paging services generally are restricted to areas reachable by local transmitters.

NPR President Frank Mankiewicz said the partnership with Mobile Communications will "combine our experience in satellite radio and theirs in running a paging service." He said that the business venture reflects "our determination to earn enough money one way or another to be free of federal funds."

The paging venture is the third association with private enterprise that NPR has announced this year, all aimed at earning enough money from profitable sidelines to replace the federal subsidies that are gradually being reduced.

Earlier, NPR announced an agreement with Western Union, operator of the Westar satellite used by NPR, to market excess satellite time, and a joint venture with National Information Utilities Corp. of McLean to transmit digital material through NPR's radio network.