How to install an eSIM
The profile is installed once and in advance. Below is the order that does not depend on the country or the operator. Menu items are named differently on different phones, so this says what to look for rather than how your firmware spells it.
At home, before the trip
It is easier to install in advance and over Wi-Fi: on most plans the validity starts neither at the purchase nor at the installation, but when the eSIM first connects to a supported network. The rule belongs to the plan, so check the plan's own before you install it.
In the phone's settings find the mobile network section and the item that adds an eSIM, then scan the QR code of the profile.
The QR code works once
The code is consumed on use: once the profile is installed, the same code will not work again.
So do not delete the profile while you need it: there would be nothing on the phone to restore it from.
On arrival
Choose the eSIM for mobile data and turn data roaming on for that profile.
Leave calls and texts on the main SIM — it does not have to come out.
Buying is not open yet
The destination catalogue and the prices already work while payment is in preparation, so today these steps can only be read in advance.
If the internet does not appear after the installation, look through the common cases.
On an iPhone
The names differ between versions of iOS: the section is labelled either "Cellular" or "Mobile Data", and the item either "Add eSIM" or "Add Cellular Plan". The order is the same in all of them.
Settings, then the cellular section.
The item that adds an eSIM.
Scan the QR code of the profile, or enter the details by hand.
On a Samsung Galaxy
One UI changes its labels between versions, so what follows is what to look for rather than the exact words on your screen.
Settings, then Connections.
SIM manager.
The item that adds an eSIM, then the QR code or the manual entry.
On a Google Pixel
Different versions of Android name the section differently while the order stays the same.
Settings, then Network & internet.
The SIMs section.
The item that adds an eSIM, then the QR code or the manual entry.
When there is nothing to scan with
The QR code can be skipped: the same profile installs from two values — the address of the SM-DP+ server and the activation code. It is the same profile and not a spare one, and it is consumed on use just as the code is.
Entering it by hand is what helps when the code is open on the very phone that would have to photograph it.
Open the same item that adds an eSIM and choose to enter the details manually.
Enter the address of the SM-DP+ server.
Enter the activation code.
When the operator asks for an APN
The APN is the access point name: the address a phone goes online through on an operator's network. A phone normally fills it in on its own and the setting is best left alone. A wrong or empty APN is a common reason for a live network with nothing loading, and that case is taken apart on the neighbouring page.
The value comes from the operator of the plan. Where none was sent, the APN is set automatically and nothing has to be changed. Where one was, it goes here:
iPhone: the cellular settings, then the eSIM profile, then its cellular data network.
Android: the connection or network settings, then the mobile network, then the access point names (APN).