The ETravelSim Vietnam eSIM connects to Viettel and Vinaphone, Vietnam's two largest mobile networks. Viettel has the widest coverage including rural northern provinces, Sapa, Ha Giang, and the central highlands. Vinaphone is the second-largest with strong urban performance. Connecting to both gives the eSIM fallback options if one network has congestion or coverage gaps in your specific location — useful on long bus rides, train routes, and motorbike loops between regions.