Earlier, the department conducted a survey on the quality of mobile services in the northern provinces of Lang Son and Bac Giang in the last two weeks of September.
Viettel topped the list as it met all six criteria, especially techniques, readiness of wireless services, and call quality.
The results reflecting the technical quality of the mobile service providers in the surveyed localities were valid at the time of the survey.
Viettel is followed by other mobile service providers, namely VinaPhone, MobiFone and Vietnamobile.
Last year, Frost & Sullivan honoured Viettel Telecom as the best mobile data service provider in Vietnam 2019./.
