Calls between mobile phones accounted for 20.5 percent of all telephone usage in Japan in fiscal 2000, up from 15 percent a year earlier, the telecommunications ministry said Wednesday.
The figure was based on a study on the roughly 144.7 billion yen worth of calls made in the period to April with fixed-line telephones, public telephones and mobile phones.
Of around 7 billion hours of phone use, the length of calls between people using ordinary telephone lines and integrated services digital networks (ISDNs) rose 12.6 percent from the previous year to roughly 5.2 billion hours.
"Usage of mobile phones and the Internet is increasing rapidly," a Ministry of Public Management, Home Affairs, Posts and Telecommunications official said.
The survey shows that the Nippon Telegraph and Telephone Corp. group has a dominant share of the fixed-line market, with more than 80 percent of calls between fixed-line phones made on NTT lines.
Meanwhile, 63 percent of mobile phone use was by NTT DoCoMo Inc. subscribers.