Last updated: 22 October 2026
Install your travel eSIM at home, on Wi-Fi, on the day you leave, and turn on its data only when you land. On most plans, ours included, the days start counting when the eSIM first connects to a network in a country it covers, not when you install it, but a few providers start the clock at installation or purchase, so read your plan's rule first.
That is the whole answer for most trips. The rest of this guide explains what "install" and "activate" mean on your phone, how the big providers' rules differ, and the switches to set before you fly.
Install, activate, start: three different moments
| Moment | What happens | When |
|---|---|---|
| Install | The eSIM profile downloads to your phone from the QR code or a one-tap link. It needs an internet connection. | At home on Wi-Fi, on the day you leave |
| Activate on the phone | iPhone or Android adds the new line and turns it on. Most phones do this at the end of the install. | Automatically, at install |
| Plan starts | The provider starts counting your days, usually at the first connection to a network in a covered country. | When you land and turn on data roaming for the eSIM |
The word "activation" causes most of the confusion. On the phone, an activated line only means it is installed and switched on. For the provider, activation usually means the plan's clock has started. Those are two different moments, and on most plans only the second one costs you days.
Our rule
Each of our plans states, before you pay, how many days it lasts and when they start counting. For most plans the days start when the eSIM first connects to a network in a country the plan covers. Our terms ask you to install with an internet connection, on the day you leave or later, so the plan does not start early.
Why the day you leave, if the clock waits for the first connection? Two reasons:
- Not every plan starts the same way, and the plan says which rule it follows. Installing on departure day means a plan with a different rule loses a few hours at most.
- A stopover can start it. If your plan covers the country you change planes in, the first connection there starts the count. That is normal, but count that day in your trip.
The QR code arrives by email within minutes of paying, with one-tap install links for iPhone and Android, so buying a few days ahead and installing on the morning you fly works well.
How other providers do it
Rules differ, so read the plan before you buy from anyone:
- Airalo says that in most cases the validity period begins when the eSIM connects to a supported network in its coverage area, but that some plans start as soon as you install the eSIM, even outside the coverage area. Each package lists its own validity policy.
- Holafly says its data plan starts as soon as you activate the eSIM's roaming data at your destination. It also warns that on iPhones with iOS 16.4 or later, installation and activation may happen together, and suggests waiting to install until you are ready.
We checked both on the providers' own help pages on 22 October 2026. If a plan says it starts at purchase or installation, install it on the day you fly, not a week before.
Why install at home, not at the airport
- You need internet to install. The eSIM downloads over Wi-Fi or data. Arrivals Wi-Fi is often slow, asks for a sign-up, or only works after immigration.
- A QR code needs a second screen. At home you can show it on a laptop or print it. The one-tap links skip this step.
- Problems are easier to fix before you go. A locked phone or a failed download is an email from your couch, not a problem in a taxi line. Our support answers every day from 07:00 to 23:00 Paris time, within 2 hours.
Before you install, check that your phone supports eSIM and is unlocked. The screens, step by step, are in our guides for iPhone and Android.
What to set before you leave home
Once the eSIM is installed, set the phone so nothing connects early and your home carrier never carries your data abroad.
On iPhone (Settings > Cellular):
- Name the new line Travel and keep your usual one as Primary.
- Keep Primary as the default line for calls and texts, and for iMessage and FaceTime.
- Keep Primary under Cellular Data for now, so you still have data at home. You switch it to Travel when you land.
- Leave Data Roaming off on the Travel line until you land.
On Android (Samsung: Settings > Connections > SIM manager; Pixel: Settings > Network & internet > SIMs):
- Keep your usual SIM for calls and texts, and for mobile data while you are home.
- Leave the travel eSIM installed. You can switch it off until the trip if you prefer.
Do not delete the eSIM if it shows "No Service" at home. That is normal on plans that only connect in the countries they cover, and a deleted travel eSIM usually cannot be installed again.
When you land
- Take the phone off airplane mode.
- Set the travel eSIM as your mobile data line.
- Turn on Data Roaming for the travel eSIM line only. A travel eSIM always connects through a local partner network, so it needs roaming on.
- Keep data roaming off on your usual line, so your home carrier does not bill you. Our guide to data roaming explains why each line has its own switch.
Give it a minute or two to find a network. If nothing connects, our guide to fixing an eSIM that is not working abroad goes through every cause in order. Still weighing a travel eSIM against your carrier's own plan? See travel eSIM vs international roaming.
FAQ
Can I install an eSIM before travel?
Yes. Install it at home on Wi-Fi, on the day you leave. On most plans the days only start when the eSIM first connects to a network in a covered country, so installing before the flight does not use up your plan. Check your plan's start rule first: a few providers start at installation or purchase.
When should I activate my eSIM for travel?
When you land. Set the eSIM as your mobile data line and turn on data roaming for it. That first connection in a covered country is what starts most plans.
How many days before travel should I install my eSIM?
On the day you leave, before you go to the airport. Installing several days ahead works on plans that start at first connection, but gains you nothing and risks losing days on a plan that starts at installation.
Does installing an eSIM start the plan?
Not on most plans. Ours, like most of Airalo's, start at the first connection in a covered country. Airalo says some of its plans start at installation, and Holafly says installation and activation can happen together on recent iPhones. Each plan states its rule.
Can I install my eSIM after I land?
Yes, if you can get online: airport or hotel Wi-Fi is enough. It is just harder to do in an arrivals hall, especially when a QR code needs a second screen. Installing at home is the safer choice.
Will my eSIM start during a layover?
It can. If the plan covers the country where you change planes and your phone connects there, the days start. If it does not cover that country, nothing happens until you reach one that it does.
Facts checked on 22 October 2026 against our terms of sale and the help pages of Airalo and Holafly.