NTT Mobile Communications Network Inc., an NTT cellular phone subsidiary known as NTT DoCoMo, announced Friday that its cellular phones users reached 20 million the day before.

NTT DoCoMo enjoyed an overwhelming share of 56.8 percent in Japan's cellular phone market as of the end of July. NTT DoCoMo, which started its mobile phone service for drivers in December 1979, has increased its number of customers largely due to deregulation -- especially after April 1994, when customers became able to purchase mobile phones instead of renting them.

The company also has been lowering its fees gradually due to intense competition in the industry, and in February 1997 topped the 10 million mark in customers, it said.