NTT DoCoMo Inc. said Friday its first-quarter net profit dropped 13 percent to 170.38 billion yen due to an expanded discount program to protect its subscriber base.

For the April-June period, the revenue of the nation's largest wireless operator slid 2.5 percent to 1.22 trillion yen.

Senior Executive Vice President Masayuki Hirata told a news conference that DoCoMo has made solid progress toward its full-year goal and did not change its earnings forecast for the current fiscal year.