Vietnamese coverage runs on Viettel and Vinaphone, delivering fast 4G — and increasingly 5G — across Hanoi, Ho Chi Minh City, Da Nang, and Hoi An and along the entire coastal corridor that most itineraries follow.

Local SIMs are cheap but require in-person passport registration, and their validity often expires before a longer trip ends; an eSIM offers a cleaner match to your actual travel dates and puts you online instantly for Grab, hostel and sleeper-bus bookings, and currency apps. Hotspot is supported for sharing on group travel.

Signal is strong across the cities and beaches but can drop to 3G in Sapa, the northern mountains, and remote stretches of the Hà Giang loop, so download offline maps for the highlands. Install at home and activate on arrival — Vietnamese carriers recognize the eSIM instantly.