TOKYO, April 18 -- Nippon Telegraph and Telephone Corp. announced plans to launch fiber optic services for Japanese households at low rates while trimming rates for high-speed asymmetric dedicated subscriber line (ADSL) connections. NTT said it would begin providing 100 Mb/s connections to users in July in certain regions of Japan. NTT said the service area would be steadily expanded over the next five years. The carrier said it would cut rates on its ADSL service to 3800 yen per month from 4050 yen per month.