Two firms in the Nippon Telegraph and Telephone Corp. group will probably lower charges for their fixed-line phone service in the face of discount campaigns by rival carriers, including KDDI Corp. and the Softbank Corp. group, sources said Friday.

NTT East Corp. and NTT West Corp. may reduce the basic charge for household users in metropolitan areas by around 200 yen from the current 1,750 yen, the sources said.

The reduction, expected to be formalized within the month, would be the first for NTT since its predecessor, the state-owned Nippon Telegraph and Telephone Public Corp., was founded in 1952.