Staying connected abroad: eSIM vs local SIM, explained
Landing in a new country with no internet is the fastest way to start a trip stressed. Here's how to be online the moment you step off the plane — and why an eSIM is usually the easiest way to do it.
You've collected your bag, you're standing in the arrivals hall, and the one thing you need — a ride, a map, a message home to say you've landed — all of it needs the internet. For years the answer was to hunt for a SIM kiosk, queue up, hand over your passport and swap a tiny plastic card into your phone. These days there's an easier way, and it doesn't involve any card at all.
What an eSIM actually is
An eSIM is simply a SIM card built into your phone. Instead of a physical chip you slot in, it's a small piece of software your phone already has, waiting to be loaded with a mobile plan. You activate it by scanning a QR code or tapping a link — no card, no tray, no fiddly removal tool. Once it's installed, your phone treats it just like a normal SIM: it connects to a mobile network and gives you data wherever you are.
The clever part for travellers is that your phone can hold more than one SIM at once. Your usual Vietnamese number stays exactly where it is, and the eSIM sits alongside it carrying your overseas data.
How it works for a trip
The whole point of a travel eSIM is that everything happens before you fly, while you're still on comfortable home wifi. The steps are straightforward:
- Buy a data plan for your destination before you leave — travellers can browse travel eSIM plans covering 200+ countries and have one ready before they fly.
- Install it at home over wifi. You'll usually scan a QR code once and your phone remembers the plan.
- Leave it switched off until you arrive, then turn the eSIM's data on when you land. You're online in seconds — no kiosk, no queue.
Crucially, your normal Vietnamese number stays active the whole time. That matters more than people expect: your bank, your e-wallet and plenty of apps send one-time passcodes (OTP) by SMS to that number, and friends and family still reach you on it. The eSIM quietly handles the data; your home SIM handles the calls and codes.
Tip: keep your physical home SIM in the phone and switched on so you still receive banking OTP and calls on your usual number — then set the eSIM as your data line. That way you get cheap overseas data without losing the texts that actually matter.
eSIM vs a local SIM vs roaming
There are three honest ways to be online abroad, and each suits a different traveller.
- Travel eSIM — the easiest for most trips. Nothing to collect at the airport, nothing to swap, and it's ready the instant you land. Best for short and medium stays and for anyone who'd rather not deal with a shop in a language they don't speak.
- Local SIM bought on arrival — can work out cheaper for a very long stay, and it gives you a local phone number, which is handy if you need to receive local calls or sign up for local services. The trade-off is the airport queue, showing your passport, and physically swapping cards.
- Roaming on your home plan — the simplest of all, because you do nothing. It's also usually the most expensive, and an unexpected bill is a poor holiday souvenir. Fine for a day or two; rarely the best value beyond that.
Does my phone support eSIM?
Most phones from the last several years do. On the Apple side, that means roughly the iPhone XS and everything newer; on Android, many recent flagships from the likes of Samsung, Google and others. The quickest way to be sure is to check your phone itself:
- iPhone: open Settings → Mobile Service (or Mobile Data) and look for an option to "Add eSIM" or "Add Data Plan".
- Android: open Settings → Network & internet (or Connections) → SIMs, and look for "Download a SIM instead" or "Add eSIM".
If you see that option, you're set. If you don't, your phone is likely a bit older and a traditional local SIM is still the way to go.
A few practical tips
- Buy a data-only plan sized to your trip — a long weekend needs far less than a two-week tour. You don't need calls bundled in if your home number is still live.
- You can top up. If you run low, most travel eSIMs let you add more data from your phone rather than starting over.
- Dual-SIM is your friend. Running the eSIM for data and your home SIM for calls at the same time is exactly what this technology is built for.
- Install before you fly. Activation sometimes needs internet, so set it up on home wifi — not while hunting for signal in a strange airport.
Done this way, connectivity stops being the first worry of a trip and becomes something you simply switched on before you left. When you're planning your next journey, we're happy to plan your trip around you — and get the small things like this sorted before you go.
Everything else, sorted too
Flights, hotels, transfers, insurance and connectivity — beSure puts the whole trip together so nothing's left to the airport. Tell us where you're going.