BARCELONA, Spain, Feb. 28, 2019 /PRNewswire/ -- At the 2019 Mobile World Congress,Vietnam's largest...
BARCELONA, Spain, Feb. 25, 2019 /PRNewswire/ -- Viettel attends Mobile World Congress 2019 inBarcel...
HANOI, Vietnam, Oct. 26, 2018 /PRNewswire/ -- Viettel's real time billing system (vOCS 3.0) was awa...