The number of 3G subscribers hit 38 million at the end of last month, or 41.3 percent of the population, according to data released by the Ministry of Information and Communications Tuesday.
It represented a 30.5 percent increase year-on-year from 29.1 million in June 2015.
The ministry is likely to license local operators to fully launch high-speed 4G services sometime in September-October this year, depending on the results of their trials, Minister Truong Minh Tuan said at a meeting the same day.
Vietnam has allowed FPT Telecom, MobiFone, Viettel, and the Vietnam Posts and Telecommunications Group to test their 4G services.
Local telecom businesses reported combined revenues of VND93.5 trillion (US$4.13 billion) in the first half.
They represented a decline of 47.4 percent year-on-year from nearly VND178 trillion ($7.87 billion) reported by the media last year.