in april 1950, the <nowiki>rds</nowiki> became the nigerian broadcasting service and introduced radio stations in lagos, kaduna, enugu, ibadan, and kano. this service was reorganized into the nigerian broadcasting corporation (nbc) on april 1, 1957, by act of parliament. its mission was to "provide, as a public service, independent and impartial broadcasting services". by 1962 the nbc had expanded its broadcast stations into sokoto, maiduguri, ilorin, zaria, jos, and katsina in the north; port harcourt, calabar, and onitsha in the east; and abeokuta, warri, and ijebu-ode in the west. each of these stations was considered a subsidiary station of a regional station. the subsidiary stations broadcast local interest programs during part of the day, and then relayed programming from their regional station during the rest of the broadcast day. national programs were broadcast from two shortwave transmitters and one medium wave transmitter located in sogunle, near lagos.