What is an eSIM and how does it work?

So what exactly is an eSIM?

A traditional SIM card is a removable plastic card that stores everything your phone needs to connect to a mobile network — operator details, identification codes and security keys. When you want to change operators, you have to pop in a new SIM card.

An eSIM does the same job. The difference is that the SIM chip is built into your phone and can't be removed. Instead, the operator gives you a digital SIM profile, you load it onto your phone, and you're ready to go straight away.

The "e" here stands for "embedded". In other words, the SIM isn't slotted in separately — it lives inside the device itself.

Here's one way to picture it: a regular SIM is like a physical key, while an eSIM is more like a smart lock you can re-program in software. Either way, the mobile network works in exactly the same way underneath.

How is an eSIM different from a physical SIM card?

The biggest advantage comes down to convenience and flexibility.

A physical SIM has to be ordered, bought from a shop and slotted into your phone. An eSIM is completely digital. You can get one online and set it up on your phone in just a few minutes.

Another important benefit is being able to store more than one profile. Most modern phones can hold several eSIM profiles and keep two of them active at the same time.

That means your personal number can stay active while you use a separate eSIM for travel at the same time.

It's worth keeping in mind that moving an eSIM to a new phone isn't quite as simple as taking a physical SIM out and putting it in. You may need to use your operator's transfer feature or re-activate a fresh profile. Even so, for most people the convenience of an eSIM easily outweighs these small limitations.

How do you activate an eSIM?

Once you've bought an eSIM, the operator creates a dedicated profile for you.

The most common method is activating with a QR code. In your phone's Mobile network settings, open "Add eSIM" or "Add mobile plan" and scan the QR code. Your phone downloads the profile details and connects to the network automatically.

Many operators now also offer setup through an app or with a single tap. This is especially handy when the QR code is already on the same phone.

During setup you can give the eSIM profile a name you'll recognise (for example, "Travel") and choose whether to use it for mobile data, calls or both.

You'll need an internet connection to download the profile, so it's a good idea to set up your eSIM over Wi-Fi before you travel.

With LimitSim eSIMs, the validity period doesn't start when you install the eSIM — it starts the moment the eSIM first connects to a mobile network in your destination country. That means installing your eSIM ahead of time won't eat into your usage.

What do you need to use an eSIM?

A device that supports eSIM

First of all, your phone needs to support eSIM technology.

Apple has supported eSIM since the iPhone XS and iPhone XR. The newest iPhone models made for the US market now work with eSIM only.

On the Android side, Google Pixel 3 and later, most newer flagship and mid-range phones in the Samsung Galaxy series, and many other modern smartphones all support eSIM.

To check whether your phone is supported, look in your settings for an "Add eSIM" or "Add mobile plan" option.

A phone that isn't carrier-locked

If your phone is locked to a particular mobile operator, you may not be able to install another operator's eSIM profile.

Most phones bought outright are unlocked. Devices bought on finance or under an operator contract may stay locked for a certain period.

An internet connection

You need an internet connection to download the eSIM profile, and Wi-Fi is the best option for this.

After setup, you'll need to turn on Data roaming for your travel eSIM. To avoid unexpected charges, it's a good idea to switch off data roaming on your main number.

The benefits of an eSIM when travelling

One of the biggest benefits is instant activation.

There's no need to hunt for a SIM card at the airport or wait in line at a shop. You buy and install your eSIM in advance, and you can start using the internet the moment you land in your destination.

Another key benefit is keeping your main phone number. Your personal SIM stays active and keeps receiving calls, texts and verification codes, while your travel eSIM is used just for mobile data.

On top of that, an eSIM helps cut down on international roaming costs. Instead of your local operator's steep roaming rates, you can use a data package you've set up in advance.

If you're travelling to several countries, you can keep different eSIM profiles on your phone and switch between them with ease.

Buying an eSIM before you travel

The easiest way to stay online while travelling is to buy your eSIM in advance.

You simply choose the country or region you're heading to, pay online and get your eSIM profile right away. There's no physical delivery and no waiting.

LimitSim offers travel eSIM packages for more than 150 countries around the world. You can pick a data package for a single country or a whole region.

You install the eSIM at home over Wi-Fi ahead of time. Since the validity period starts from the moment the eSIM is first activated in your destination country — not from the date you buy it — you won't lose any of your usage days.

It's exactly this convenience — being ready ahead of time, arriving with internet already sorted and keeping your main number active — that makes an eSIM one of the most practical choices for travel.