In the city

Ho Chi Minh City is the easiest coverage in the country on every major network, Viettel included. Grab, Maps, and chat work in District 1, around the backpacker streets, in Thao Dien, and on the ride in from Tan Son Nhat. Indoor malls and the basement of a hotel are the usual dead spots, and they are building problems. High floors can be better than the lobby or worse, depending on which side of the tower faces a site. None of that is fixed by buying a second eSIM.

Data use in the city is mostly small and constant. A Grab across town is a few megabytes. An hour of looking at the map while you walk is tens of megabytes, not gigabytes, unless you are streaming. The 5GB day is sized for that plus photos and music. It is not sized for downloading a season of television in the hotel. When the allowance ends, data ends, until 23:59 GMT+7.

Out of the city

The highway toward Vung Tau and the main roads into the delta stay usable. The romantic version of the delta, a boat and a dirt track, is where you should expect pauses. Ferry crossings drop signal because there is water and distance, not because the eSIM deactivated. Phu Quoc is a flight or a long bus-and-ferry away and uses the same profile once you arrive. Domestic terminals at Tan Son Nhat, including Terminal 3, do not need a new install.

Vinaphone is strong in this city. If your only plan were three days in District 1, a roaming eSIM on VNPT would also load Grab. The local Viettel line is the one you still have on day four when the itinerary changes. That is the practical difference, and it is the one the comparison page is about. It is not a claim that Viettel won every national speed trophy. It did not. Vinaphone led nPerf’s overall 2026 score, and Vinaphone led Opensignal’s 5G download number.