The most important thing to know before buying a vietnam esim: the three providers that dominate search results — Airalo, Holafly, and Ubigi — all host on Vinaphone (VNPT). Vinaphone is fast in Hanoi, Ho Chi Minh City, and Da Nang, and it's the right call for city trips. But it loses signal for long stretches on the Ha Giang Loop, on Sapa mountain passes, and across remote northern provinces. Viettel — the military-owned carrier holding roughly 56% of Vietnam's mobile subscribers — is the only network with reliable coverage on those itineraries. If you're heading into the mountains or the rural north, you need a Viettel-hosted eSIM or a local Viettel SIM. That choice is what this guide is about. For city and beach travel (Hanoi, HCMC, Da Nang, Hoi An, Ninh Binh, Ha Long Bay), any Vinaphone-based esim vietnam product works well. For the Ha Giang Loop, Sapa villages, Cao Bang, and outer islands, the best esim for vietnam must be Viettel-hosted: Gigago Viettel, Klook Viettel, or a local Viettel tourist SIM bought at the airport. All prices and plans in this guide were verified June 2026. For broader context, see our full 2026 eSIM provider ranking. Airalo Vietnam is 4G/LTE only on the Vietnam product; Holafly and Ubigi reach 5G in cities but rural areas are 4G regardless of carrier. For a complete breakdown of every provider, see our 2026 eSIM provider ranking. Viettel is owned by Vietnam's Ministry of National Defence and holds roughly 56% of the country's mobile subscribers. Unlike commercial carriers that build where density justifies the return, Viettel was required to cover deep rural valleys, remote border zones, and coastal islands for national security. That infrastructure decision is now the single most important fact for any traveler heading off the tourist circuit. Ha Giang Loop. Between Dong Van, Meo Vac, Lung Cu, and the Ma Pi Leng Pass, Viettel is the only network with signal in district towns and across most of the road. Vinaphone loses signal for long stretches. The Dong Van–Meo Vac road crossing Ma Pi Leng along the Nho Que canyon is the longest consistent dead zone on the standard loop — sheer limestone walls block every carrier. Download offline maps before leaving Ha Giang city. Sapa. All networks work in town and Lao Cai. On mountain passes and in trekking villages (Cat Cat, Ta Van, toward Fansipan), Viettel stays usable while Vinaphone and Mobifone drop. Cao Bang / Ban Gioc. Eastern karst border zone — Viettel retains coverage where others fail. Phong Nha-Ke Bang. Inside caves (Son Doong, Paradise, Phong Nha) = zero signal on every network. At the surface, Viettel holds best. Phu Quoc and ferry routes. Viettel is strongest on the north and east roads; best island and coastal footprint for outer islands and ferry crossings. Mekong Delta. Viettel advantage in rural districts; Mobifone reportedly fast in larger delta towns. The practical rule: if your itinerary stays in Hanoi, HCMC, Da Nang, Hoi An, and Ha Long, any Vinaphone-based eSIM is fine. If you're doing the Ha Giang Loop, remote Sapa, or the outer islands, get a Viettel-hosted eSIM or a local Viettel tourist SIM. Do not save $5 and lose your map in a rainstorm on Ma Pi Leng. Tip: For app setup and eSIM installation walkthroughs, see our Airalo review. Vietnam tightened prepaid mobile registration in stages. Decree 49/2017/ND-CP requires foreigners to present a valid passport for any physical SIM purchase. Circular No. 08/2026/TT-BKHCN — effective April 15, 2026 — added mandatory facial biometric verification cross-checked against the National Resident Database for every new mobile subscription. Buying a SIM at an airport counter now means a passport scan plus a facial biometric check. An international travel eSIM bypasses this entirely. Airalo, Holafly, Ubigi, Gigago, and Klook eSIMs are foreign-issued profiles that roam onto Vietnamese networks — classified as international roaming, not domestic prepaid lines. No passport handover, no kiosk, no biometric. You install via QR code from home before you fly. Vietnam does not enforce IMEI registration that blocks foreign tourist phones; your phone must be carrier-unlocked. If you want a local Viettel SIM for rural coverage, bring your passport — the kiosk process is straightforward at HAN, SGN, and DAD. Heads up: The facial biometric requirement is new as of April 2026 — the process is different from previous visits. Travel eSIMs avoid it entirely. Vietnam rolled out commercial 5G in late 2024 and early 2025. Viettel launched in October 2024 on the 2,600 MHz band; VNPT-Vinaphone followed in December 2024 (3,700–3,800 MHz); MobiFone went live in March 2025. By February 2026, the Ministry of Science and Technology reported approximately 91.2% population coverage — a figure that is heavily city-concentrated. In practice, the speeds are impressive where 5G exists. Da Nang averaged 671.18 Mbps on 5G downloads in October 2025, the fastest city in Vietnam (VNNIC i-Speed data), and the national 5G average hit 594.81 Mbps in January 2026. The critical caveat for eSIM buyers: travel eSIMs roaming on Vietnamese networks often receive 4G/LTE only, not 5G. Airalo Vietnam is explicitly listed as 4G/LTE on its product page. In rural and mountain areas — precisely where network selection matters most — your phone falls back to 4G regardless of carrier. A solid 4G Viettel signal beats a nominal 5G Vinaphone bar that disappears on the mountain pass. The cheapest way to get Viettel coverage is a local tourist SIM at the airport kiosk. Viettel 5G120H = 1.5 GB/day for 30 days at 120,000 VND (~$4.80); Viettel 5G180H = 5 GB/day for 30 days at 180,000 VND (~$7.20). MobiFone's Happy Tourist HP2 gives 8 GB for 30 days at roughly $4.39. These prices are hard to beat and give you full Viettel network coverage — but you must hand over your passport and complete a facial biometric scan at the kiosk. The online alternative: Klook Viettel eSIM (~$15/7d) or Gigago Viettel ($13.90/30d). Both are explicitly Viettel-routed, install via QR before you fly, and require no passport at any kiosk. You pay a modest premium over the local SIM price for the convenience of skipping the airport queue. For most rural travelers, the decision is simple: do you want to deal with the biometric kiosk after a long international flight, or pay a few dollars more to walk straight out of arrivals with connectivity already working?