Four minutes, before you leave home
Set up your Vietnam eSIM
Install the profile on your own wifi, land already connected, and skip the counter queue. Plus the one setting that matters near the Chinese border.
Will your phone work? two checks, thirty seconds
- Dial *#06#. A panel appears with your IMEI and, if the phone supports eSIM, an EID. No EID means no eSIM, and your route is a local SIM card instead.
- Check it is unlocked. A carrier-locked handset accepts neither a Vietnamese SIM nor a travel eSIM. In the US, carriers must unlock on request once the device is paid off, and it takes a day or two, so do this before you book anything.
- The rough rule on models: iPhone XR, XS and everything newer; Google Pixel 3 and newer; Samsung Galaxy S20 and newer plus recent Z Fold and Flip models. Chinese-market variants of Android phones frequently have the eSIM hardware disabled.
Installing the eSIM at home iPhone and Android
iPhone
1. Settings → Cellular → Add eSIM.
2. Use QR Code, and scan the code from the provider's email. Most providers also offer a one-tap install link that skips the scan entirely.
3. When asked, label the line something you will recognise at 2am. "Vietnam" beats "Secondary".
4. Set Default Voice Line to your home number and Cellular Data to the Vietnam line. Turn Data Roaming ON for the Vietnam line only, because a travel eSIM technically roams, and OFF for your home line.
Android
1. Settings → Network & internet → SIMs → Add eSIM or the + next to SIMs. Samsung phrases it as "Add mobile plan".
2. Scan the QR code from the provider's email.
3. Under SIMs, set Mobile data to the Vietnam line and Calls to your home line.
4. Open the Vietnam line's settings and turn Roaming ON for it. Turn roaming OFF on your home line, which is the toggle that stops a $12-a-day charge.
Install at home, not at the airport. Vietnamese airport wifi works, but a QR code you cannot scan because the email will not load is a bad way to start a trip, and the plan does not begin counting until it connects to a Vietnamese network anyway.
What to do when you land Noi Bai and Tan Son Nhat
- On the plane, before doors open: turn airplane mode off and give it a minute. Most eSIMs attach during taxiing.
- Check the status bar shows a Vietnamese carrier name rather than your home one. Vinaphone, Viettel and MobiFone are the three you might see.
- Open Grab before you leave the terminal. If it loads a map and finds cars, everything works. If it does not, you are still inside a building with free airport wifi and a 24-hour carrier counter twenty metres away, which is the best possible place to discover a problem.
- Do not delete your home line. Keep it active for incoming calls with its data roaming off. Vietnamese hotels and Grab drivers do sometimes ring a foreign number.
The manual network trick and why it matters most in the north
Automatic network selection usually works. Two situations in Vietnam where it does not, and both are fixed the same way.
Nothing connects on arrival. Go to Settings → Cellular → Network Selection (iPhone) or SIMs → the Vietnam line → Automatically select network (Android), switch it off, and pick from the list. Try Vinaphone first, since that is what the brands who publish a partner are on, then Viettel, then MobiFone.
You are near the Chinese border and the phone has gone silent. In Ha Giang, Cao Bang and along the northern frontier, handsets sometimes latch onto a Chinese network across the border, which your Vietnamese plan cannot use. The symptom is bars with no data. Same fix: manual selection, pick the Vietnamese carrier by name.
Symptom to fix the eight things that actually go wrong
| Symptom | Most likely cause | Fix |
|---|---|---|
| QR code will not scan | Screen brightness, or the code already used once | Use the provider's manual entry (SM-DP+ address and activation code), which is in the same email. |
| eSIM installed, no service | The line is off, or roaming is off for it | Turn the line on, then turn Data Roaming ON for that line specifically. A travel eSIM roams by design. |
| Bars showing, no data | Wrong line set as the data line, or a foreign network | Set Cellular Data to the Vietnam line. Near the border, check the carrier name and select the Vietnamese one manually. |
| Works in Hanoi, dead in Ha Giang | You are on VNPT and this is a coverage gap | Not a fault. A Viettel profile is the only fix, about $5. |
| Data ran out on day four | Photo backup syncing over cellular | Turn off automatic photo and video upload over mobile data. This is the most common cause by a distance. |
| Hotspot will not share | Holafly's 1GB daily tethering cap | Nothing to fix on the phone. The cap is in the plan. |
| Home number stopped receiving calls | The home line was deleted or switched off | Re-enable it as the default voice line, with its data roaming off. |
| Plan expired before the trip ended | Validity started at first connection, not at arrival | Check the start date in the provider's app; short-validity plans (3 and 7 days) are where this bites. |
If none of these fixes it, contact the provider before buying anything else. Every brand we link has a refund policy for a plan that never activated, and the ones with the best support records are Saily and GigSky. See the comparison.
Setup questions answered
When should I install my Vietnam eSIM?
At home, on your own wifi, any time before you fly. The plan does not start counting until the profile first connects to a Vietnamese network, so installing a week early costs you nothing and removes every point of failure from arrival day.
Do I need to turn on data roaming?
Yes, for the eSIM line only. A travel eSIM works by roaming onto a Vietnamese network, so roaming must be on for that line. Turn it off for your home line, which is the setting that prevents a $12-a-day charge.
Can I keep my home phone number?
Yes, and you should. Keep the home line active as your default voice line with its data roaming off, and set the eSIM as the data line. Calls and texts still reach your normal number and cost nothing to receive on most US plans.
Why does my phone show bars but no internet in Vietnam?
Usually one of two things: the wrong line is set as the data line, or the handset has attached to a network your plan cannot use, which happens near the Chinese border in Ha Giang and Cao Bang. Both are fixed by setting network selection to manual and picking a Vietnamese carrier by name.
Can I install two eSIMs on one phone?
Yes, on any modern handset, and for Vietnam it is often the right move: a travel eSIM for the cities and the coast, and a Viettel profile for the mountains. You switch which line carries data in settings, in two taps.
What if the eSIM does not work when I land?
You landed in one of the best possible places for this to happen. Both main airports have free wifi and 24-hour carrier counters past immigration, so you can troubleshoot on wifi and buy a local SIM in ten minutes if you need to. Work through the symptom table above first.
Install it tonight, land connected
Airalo publishes VNPT as its Vietnamese network, sells 10GB for $18.00 over 30 days, and the plan does not start counting until you actually arrive.
See Airalo Vietnam plansSources & freshness: Device compatibility from Apple, Google and Samsung eSIM documentation. Menu paths verified against current iOS and Android releases, September 4, 2026. Airport wifi and carrier counter presence at Noi Bai and Tan Son Nhat from current airport information. Fixes drawn from provider support documentation and traveler reports through September 2026.