NTT Docomo Inc. announced Wednesday that it will launch the nation's first high-quality voice call service using fast LTE networks in June, aiming to halt the decline in revenue from voice calls.

With new fixed-price voice call plans set to start in June and the high-quality service named Voice over LTE, or VoLTE, Docomo is pushing the voice call service in an era in which people increasingly communicate with messaging services like the Line app and social network services such as Facebook.

"Voice calls — we'd like (people) to think of them again as a basic telecommunications" component, Docomo President Kaoru Kato said at a news conference Wednesday.