What is an eSIM and how does it work?

What is an eSIM? The simple definition

An eSIM is an electronic chip soldered onto your phone's motherboard when it is manufactured. It replaces the physical SIM card: instead of inserting a piece of plastic into a tray, you download a carrier profile onto it, meaning your plan as a secure file. The "e" stands for "embedded": the chip never comes out, it is its content that changes.

Technically, this chip is called an eUICC (embedded Universal Integrated Circuit Card). It uses the same electrical interface as a classic SIM and performs the same functions: identifying your line on the network, securing the connection, carrying your number. To the mobile network, an eSIM and a physical SIM card are indistinguishable.

eSIM is not an exotic technology: it is a global standard published by the GSMA, the association of the world's mobile operators, whose first consumer specification dates back to 2016. Since then, Apple, Samsung and Google have rolled it out across their smartphones, and some recent models, like iPhones sold in the United States, no longer have a SIM tray at all.

For perspective: the SIM card has existed since 1991 and has only been shrinking, from credit-card size to mini-SIM, then micro-SIM, then nano-SIM. eSIM is the logical next step: size zero, fully digital.

How does an eSIM work?

How an eSIM works fits in one sentence: your carrier sends you your plan over the internet, and your phone installs it on its built-in chip. In practice, when you sign up, the carrier generates an eSIM profile and sends it to you, most often as a QR code.

Activation then happens in one of three ways: scanning the QR code with the phone's camera, going through the provider's app which installs the profile automatically, or entering an activation code manually. In all three cases, the phone downloads the profile, the line shows up in the settings, and you can call, text and use data like with any SIM.

On iPhone, everything happens in Settings, then Cellular, then "Add eSIM". On Android, head to Settings, Network & internet, then SIMs. Count a few minutes, stopwatch in hand, where a physical SIM card requires a store visit or postal delivery.

Another key point: an eSIM stores several profiles at the same time. Apple states on its official support page that a compatible iPhone manages eight or more eSIMs in memory, two of them active simultaneously on recent models. You can therefore keep your main line and stack spare travel plans; we detailed those limits in our article on how many eSIMs an iPhone can have.

eSIM vs physical SIM card: the real differences

Same role, two formats. Here is what actually changes between a physical SIM card and an eSIM, point by point.

Format: the classic SIM is a plastic card you insert into a tray; the eSIM is an invisible chip, already in the phone. Nothing to receive, nothing to punch out, nothing to lose.

Getting started: a physical SIM is bought in a store or arrives by mail, sometimes taking days. An eSIM profile downloads immediately after signing up, even on a Sunday night at 11 pm.

Switching carriers: with eSIM, moving to a competitor no longer means waiting for a new card. You sign up, you scan, the old line deactivates. Number portability follows the same rules as before.

Theft and loss: an eSIM cannot be removed from the phone. If it is stolen, the thief cannot eject your SIM to reuse it or cut off the device's location tracking, a real plus for recovering a stolen phone.

The backup phone: this is eSIM's weak spot. If your phone breaks down, you cannot slip your SIM into an old flip phone while it gets repaired: you have to request a profile transfer from the carrier, which can take time with some of them.

Number of lines: one physical SIM per tray, but several eSIM profiles stored on the same chip. Dual SIM becomes the norm: two active numbers on a single phone, without a second device.

The pros and cons of eSIM

eSIM stacks up real advantages, but it also has concrete limits that a salesperson will not spontaneously detail. The honest assessment, both ways.

On the pros side:

✅ Activation in minutes, with no store visit or mail.

✅ Two lines on one phone: personal plus work number, or home line plus local data when travelling.

✅ Easier carrier switching, with no card handling.

✅ Impossible to lose, break or steal separately from the phone.

✅ Up to eight or more stored profiles, switchable in the settings.

✅ Less plastic produced and shipped.

On the cons side:

❌ You need a compatible smartphone, so a model released after roughly 2018.

❌ If the phone breaks, there is no card to move to a backup device: transferring the profile depends on the carrier's procedure and can take from a few minutes to 24 or 48 hours in some cases.

❌ Some carriers charge a few euros for issuing or replacing an eSIM profile.

❌ A carrier-locked phone may refuse a competitor's eSIM until it is unlocked.

Overall, the balance clearly tips in eSIM's favour for everyday use, and even more so for travel. The only real scenario where the physical card keeps the edge is a quick fix on an old phone.

Which phones are eSIM compatible?

eSIM compatibility now covers the vast majority of recent smartphones. On the Apple side, every iPhone since the iPhone XS, XS Max and XR, released in 2018, supports eSIM. On the Samsung side, support starts with the Galaxy S20 in the S range. On the Google side, it goes back to the Pixel 3. Mid-range models followed later: on a phone under 300 euros, checking remains essential.

Watch out for regional variants too: the same model can be eSIM compatible in Europe but not in some Asian countries, and vice versa. We listed every Apple model concerned, generation by generation, in our guide to eSIM-compatible iPhones.

To check your own phone in ten seconds: dial *#06# on the phone keypad. If an EID number appears (around thirty digits), your phone has an eSIM chip. You can also look in the settings: "Add eSIM" on iPhone, or "Download a SIM" on Android, confirms compatibility.

The rat's advice: check the EID before buying an eSIM plan, not after. Every year, travellers buy a travel eSIM for a phone that is incompatible or carrier-locked, and not every brand refunds a profile that has already been issued. Ten seconds of checking versus a wasted plan, the maths is quick.

eSIM with your carrier: how to switch

Most major carriers now offer eSIM on their consumer plans, from the big four French networks (Orange, SFR, Bouygues Telecom, Free Mobile) to many virtual operators, and the same goes across Europe and North America. In other words, you can move your main line to eSIM with most carriers on the market.

The eSIM profile is often included, but some carriers charge a few euros for issuing or replacing it, just like a physical SIM card used to be. The plan itself does not change price: eSIM or plastic, your subscription stays the same.

To switch an existing line, the procedure runs from your customer account: you order an eSIM profile, the carrier deactivates the physical card, and you scan the QR code you receive. Recent phones can also transfer an eSIM from one device to another directly, for instance when changing iPhones.

eSIM for travel: the game-changing use case

If eSIM is booming, it is first and foremost thanks to travel. The principle: you keep your home line active to receive calls, texts and banking verification codes, and you add a local travel eSIM that carries the data. The result: internet at local rates as soon as you land, without touching your carrier's roaming fees, which remain steep outside your home region.

Specialised providers sell these data plans by country or region, with no commitment, activatable online in minutes. Airalo lines up the widest catalogue of destinations. Holafly focuses on unlimited data, framed by a fair use policy. Saily builds a VPN into its app. voilà, a French provider, plays the value-for-money card with per-GB rates among the lowest recorded on our comparator, an eSIM that is easy to install paired with an easy-to-use app, and human customer support, available 24/7.

No provider is the cheapest across all destinations: per-GB price gaps vary widely from one country to the next. The right habit is to compare offers for your exact destination before buying, at equal volume and duration.

The rat's advice: install your travel eSIM before departure, comfortably on your home Wi-Fi, but only activate it on arrival if validity starts at activation. You avoid the stress of scanning a QR code on dodgy airport Wi-Fi, and you do not burn plan days while sitting on the plane.