What is an eSIM? The simple definition, and everything it changes

How it works fits in one sentence: your carrier sends you your plan over the internet, and your phone installs it on its built-in chip. When you subscribe, the carrier or provider generates a unique eSIM profile, most often materialised as a QR code, sometimes pushed automatically through its app.

When you scan that code, the phone downloads the profile and stores it on the eSIM chip. The line then appears in the settings, exactly as if you had just inserted a card: you can call, text and use data. The chip can store several profiles at once (eight or more on a recent iPhone), with one or two active depending on the model: handy to keep your main line and stack travel plans on standby.

One important point: an eSIM profile is generally single-use. Once installed, it is tied to the phone; if you delete it, the same QR code will no longer work and you will need a reissue. That is the main precaution to know, we come back to it in the downsides.

Both cards provide the same service: carrying your mobile line. All that changes is the medium, and it shows in everyday use:

In short: the physical SIM card keeps a single practical advantage, moving instantly from one phone to another. On everything else, speed, flexibility, travel, multi-line, the eSIM has taken the lead. That is why carriers and manufacturers alike are gradually moving to all-eSIM.

Activation takes about two minutes. You need three things: a compatible, unlocked phone, a Wi-Fi connection, and the QR code or activation link supplied at purchase. Here is every method, step by step.

Activating an eSIM on iPhone

Four possible methods, from the most common to the most specific. The full official walkthrough is also on the Apple support page.

With a QR code (the most common method)

1. Connect the iPhone to Wi-Fi, then open Settings > Mobile Data.
2. Tap "Add eSIM", then "Use QR code".
3. Scan the QR code received by email with the camera, then tap the "Mobile plan detected" notification. Tip: if the QR is displayed on the iPhone's own screen, a long press on it offers "Add eSIM" (iOS 17.4 and later).
4. Name the line ("Travel", "Work"...) and choose which line carries mobile data. The profile downloads, the line appears in the settings: done.

Through the provider's app

1. Buy your plan in the provider's app (carrier or travel eSIM).
2. Tap "Install eSIM" in the app: the profile installs itself, with no QR code.
3. Confirm the new line when iOS asks, then check which line is selected for mobile data.

By transfer from an old iPhone

1. On the new iPhone, open Settings > Mobile Data > Add eSIM, then "Transfer from a nearby iPhone".
2. Keep both iPhones unlocked side by side, Bluetooth on, and confirm the transfer on the old one.
3. The line moves to the new phone and deactivates on the old one. Careful: prepaid travel eSIMs are often excluded from transfer, they stay tied to their first device.

By converting your physical SIM card

1. Open Settings > Mobile Data, tap your current line, then "Convert to eSIM" (only visible if your carrier supports it).
2. Confirm: the profile installs and the plastic card deactivates for good.
3. Remove the card from the tray, it no longer serves. The tray is free for another card.

Day to day, the main point is flexibility: switching carriers without waiting for a card, adding a work line without a second phone, converting your line to free up the SIM tray. But it is when travelling that the eSIM really changes the game: instead of paying your home plan's roaming at full price or hunting for a local SIM card on arrival, you buy a data plan for your destination online, install it before leaving, and it activates on landing.

That is exactly what our pages compare: eSIM plans from every provider (Airalo, Holafly, Saily, Ubigi, Nomad, voilà...), destination by destination, with hand-checked prices. To see what it costs in practice, head to the destination comparator or the page of compared eSIM providers.

Let's be honest, the technology has its limits too. None is a deal-breaker, but better to know them upfront:

• Changing phones is less instant. A physical card moves in ten seconds; an eSIM requires a transfer or a profile reinstallation, sometimes via the carrier.
• A profile is often single-use. Deleted by mistake, it cannot be reinstalled with the same QR code: you need a reissue, sometimes billed by certain carriers.
• Not every phone is compatible. Entry-level models and pre-2019 devices often go without, as do some regional variants (iPhones sold in mainland China, for instance).
• Not every carrier offers it. France's four major networks support it, but several budget MVNOs still only issue physical cards, as we detail in our article on eSIM at La Poste Mobile.
• Troubleshooting goes through the internet. Installing or reinstalling a profile requires a connection (usually Wi-Fi): with no network at all, you cannot bring a line back from scratch.

For everyday use, and especially for travel, these limits weigh little against the advantages: it is a trade-off you win comfortably, provided you follow one simple rule, never delete an eSIM profile unless you are sure you no longer need it.

The universal test takes thirty seconds and works on iPhone and Android alike: dial *#06# on the call keypad. If a 32-digit EID number shows with the IMEI, your phone has the eSIM chip. If there is only the IMEI, it does not.

A second check lives in the settings: on iPhone, the "Add eSIM" option in Settings > Mobile Data; on Android, an "Add eSIM" entry in the SIM settings. And remember carrier unlocking: a phone locked to a carrier can refuse another provider's eSIM.

On iPhone, the eSIM has been around since late 2018: every model since the iPhone XS, XS Max and XR supports it, SE 2020 and 2022 included. Since the iPhone 13, two eSIMs can be active at the same time, and the iPhone Air takes the logic all the way: sold without a SIM tray, it runs eSIM only, like the American models since the iPhone 14.

Apple also has the most polished features on the market: converting the physical card to an eSIM from the settings, transferring a line from one iPhone to another without contacting the carrier, and eight or more stored profiles. The full list, model by model with the traps by country of purchase, is in our eSIM compatible iPhone guide, and the detail of active lines in how many eSIMs on an iPhone.

On the Android side, it is exactly the same technology, arriving with the Google Pixel 3 then spreading: Samsung Galaxy since the S20 (S, Z Fold, Z Flip series and some A models), Google Pixel since the Pixel 4, and the recent mid-range and high-end from Xiaomi, Oppo, Motorola, Sony, Honor or OnePlus. The only real difference with the iPhone: menu labels change from brand to brand.

Watch out, however, for the two Android-specific traps: the entry level (many Redmi and Galaxy A remain physical SIM only), and regional variants, the same model existing with and without eSIM depending on the country of sale. The *#06# test and our compatibility checker settle it in every case.

The best way to understand the eSIM is to see what it costs for your next trip: plans compared provider by provider, prices checked by hand.