Travel eSIMs: how they work and when to install

A travel eSIM replaces the two bad options for data abroad: paying your home carrier's roaming rate, or finding a shop in a country you just landed in and buying a local SIM with your passport. It is a profile you download and install, and it works the moment you arrive — if you set it up at the right time.

Install it before you fly

This is the thing to get right. Downloading the eSIM profile requires a working internet connection. If you wait until you land, you need data to get data — and airport wi-fi that requires an SMS code you cannot receive is a genuinely common way to be stuck.

On most plans the validity clock starts when the profile first connects to a network in the destination, not when you scan the QR code. So installing at home on wi-fi costs you nothing and removes the whole problem. Scan it the day before you travel and leave it switched off until you arrive.

Check your phone first

Two requirements: the handset must support eSIM, and it must not be carrier-locked. Most iPhones from the XS onward and most recent Android flagships support it; Apple publishes its own list of carriers and devices that support eSIM. A carrier-locked phone will refuse the profile even if the hardware supports it, which surprises people who have never tried to use a second line.

What an eSIM will not do

These are data plans. You do not get a local phone number, which matters more than people expect: an SMS verification code from a bank or an airline needs a real line, and a data-only eSIM cannot receive one. Calls and messages through WhatsApp, Signal or FaceTime work perfectly well on the data.

Your normal SIM stays in the phone for calls and texts on your home number. Turn its data roaming off — otherwise your carrier can quietly bill you alongside the plan you just bought.

Regional or global

A regional plan is cheaper per gigabyte; a global one is one profile that keeps working as you cross regions. If your whole trip is inside Europe or the United States, buy the regional plan — Europe or the USA — rather than paying the global premium for coverage you will not use. The global plan earns its price on multi-stop trips, and on trips where you genuinely do not know the itinerary yet.

Whichever you pick, check the covered-countries list against your actual route rather than the headline number. A hundred countries is a large number that may still exclude yours.

When the data runs out

It stops. A prepaid travel plan has no overage billing, which is the point — there is no mechanism to charge you more, because there is no payment method attached to it. Practically, that means data can end mid-trip with no warning beyond whatever the plan's own portal shows, so check usage every few days rather than discovering it at a border.

Buying a second plan is usually straightforward and often cheaper than buying the largest allowance up front for a trip whose length you are unsure of. Two 5 GB plans bought a week apart beat one 20 GB plan that expires with half of it unused.

Topping up someone else's phone is a different thing

Worth separating, because the two get confused. An eSIM is a data profile you install on your own device. A mobile top-up is credit applied directly to a phone number, often someone else's in another country. Top-ups cannot be reversed once applied, so the number and the operator have to be right the first time.

For paying, the networks guide covers the cheapest way to send a small amount, and the main guide covers the rest.