The company also plans to spend about Bt5 billion on marketing campaigns this year, up 20 per cent from last year.
He said the competition this quarter would be tough.
He added that in the short term the company would focus on defending its share of the prepaid cellular-service market.
In the second quarter, DTAC voice-service usage declined, while data usage increased to 60 per cent of the market from 58 per cent in the previous quarter.
DTAC currently has more than 3.5 million subscribers to its fourth-generation service, increasing from 2.9 million in the first quarter, and aims to have 6 million subscribers by the end of the year.
DTAC recently increased its bandwidth on the 1,800-megahertz spectrum for 4G service to 20MHz for Bangkok and vicinity, up from 15MHz previously. It now completely covers the remaining provinces nationwide with 15MHz of 4G-1,800MHz. Besides its 1,800MHz bandwidth, DTAC uses 5MHz of a 15MHz band on the 2.1-gigahertz spectrum to offer 4G wireless service.
DTAC posted a sharp drop in net profit in the second quarter to Bt141 million, declining 90 per cent year on year, due to higher depreciation and amortisation, lower EBITDA (earnings before interest, taxes, depreciation and amortisation) and a one-time restructuring cost of Bt394 million.