What is an eSIM and how does it work?

In 2022, eSIMs reached a wide audience when Apple announced its newest iPhone, the iPhone 14 series, would only support eSIM in the United States. Following Apple's announcement, Three Ireland rolled out eSIMs in 2023.

But what exactly is an eSIM, and is it really as good as they say?

What is an eSIM?

Until 2022, all mobile phones used SIM cards to allow us to call people, send messages and connect to the internet on the go. SIM cards identify you and enable your access to your chosen network.

SIM stands for Subscriber Identity Module. eSIM is the next generation of SIM cards. The biggest difference is that instead of physically inserting a chip into your phone, it’s digitally embedded directly into your device. Embedded is what the “e” in eSIM stands for.

How does an eSIM work?

Activating an eSIM can differ slightly depending on your network and device. As the eSIM is digitally built into your phone, you don’t need to wait for a SIM card to arrive to start using your plan.

Instead, you’ll receive a QR code from your network provider, or you’ll be directed to activate your eSIM through your device’s settings. Your phone will download your eSIM profile, which connects you to the mobile network, and once it’s authenticated, you’ll have access to your mobile plan. Three offers a range of eSIM plans for all needs.

What are the benefits of eSIM?

It’s understandable to ask “why switch to eSIM?” and honestly, it’s not just some new fancy technology. It really does have some amazing benefits. Below are our favourites.

Easy to set up

Setting up an eSIM is easy, even with the steps differing slightly from network to network or phone to phone. Generally, it’s as simple as scanning a QR code and following the steps on screen. If you have a compatible phone, setup can even be done through your device settings.

No physical SIM card needed

Physical SIM cards can develop issues, meaning after a couple of years, it’s likely you’ll need to carry out a SIM swap because of wear and tear. With an eSIM, that’s a thing of the past.

Ability to have multiple phone numbers on one phone

Some networks and phones allow multiple profiles on a single phone. This means you’ll be able to have a profile for your personal number and a separate profile for your work number on the same device, for example. Availability will depend on both your network and your phone support.

Convenient when travelling

It’s taken a few years for everyone to truly feel this benefit. But now with smartphone manufacturers and networks embracing eSIMs, grabbing a plan on the go has become very easy.

You’re able to enjoy all the benefits of your Three plan at home but then grab an eSIM plan when travelling internationally from a company like Hello Globe. This gives you a more affordable way of calling home or using Google Maps while on holiday.

One thing to remember is that eSIM functionality may include network SIM locks. That means you may need to unlock your phone before you can use it with another network.

More secure

eSIMs have advanced security features that traditional SIM cards just don’t have, such as inbuilt resistance to unauthorised cloning. The embedded chips are also tamper resistant, giving your data another layer of protection.

An eSIM can’t be separated from your phone, meaning if the device is lost or stolen, the SIM can’t be accessed with another phone to bypass your phone security features. As they can’t be separated, Find My Device services can also be more effective.

Which phones support eSIM in Ireland?

Most modern smartphones are eSIM compatible but if you’d like to check, you can check the product page for your device in our phone shop or in our device guides.

Apple iPhone eSIM compatible phones

All Apple iPhones from iPhone 11 onwards with iOS 26 or newer are eSIM compatible. Please be aware that not all phones are eSIM compatible, so if you are in the market for an eSIM compatible device, make sure to check the device specifications before purchasing.

Samsung eSIM compatible phones

Many Samsung phones produced after 2020 are eSIM compatible, particularly Samsung’s flagship Galaxy S range, starting from the Samsung Galaxy S20. While most are eSIM compatible, not all are, so check the specifications before adding to your cart.

Google Pixel eSIM compatible phones

Most Google Pixel phones from the Pixel 4 range onwards can support eSIM. Visit our online shop to see a list of the eSIM compatible Google Pixel phones currently available.

Other eSIM compatible phones

There are many other phone brands that are eSIM compatible, such as Oppo, Xiaomi and Honor. While most of the models released in the last couple of years are eSIM compatible, please keep in mind that not all are.

If you’re wondering if your device is eSIM compatible, dial *#06# on your device’s keypad. This will prompt a popup displaying your phone's IMEI. If you also see an EID number, then your phone is eSIM compatible.

You can find the latest list of supported eSIM phones. Already a Three customer? You can now replace your traditional SIM card with an eSIM.
 

How to activate your eSIM

To activate your eSIM, there are three options. For anyone who is activating an eSIM for the first time, you can either activate by QR code or by On Device Activation (ODA). Anyone who is looking to transfer their eSIM from one device to another can do so by QR code or by On Device Transfer (ODT).

Activating by QR code

If you’re new to Three and you’re looking to activate an eSIM, you can simply request an eSIM as part of your purchase journey. Otherwise, existing customers can request an eSIM by visiting Replace My SIM.

Once you’ve requested an eSIM, you’ll receive an email containing a QR code. Simply scan the QR code and follow the directions on screen to activate.

Activating by ODA

Activating by ODA is only available for first-time connections with Three if you’re purchasing an eSIM compatible device. If your selected device is compatible and you’ve selected eSIM at checkout, you’ll be sent an email with step-by-step instructions on how to activate your new eSIM.

These steps are easy to follow and are part of your new phone's setup journey.

Activating by ODT

ODT can be used by anyone using a compatible device who is looking to:

1. Move from a physical SIM to eSIM and keep your current phone.
2. Move from a physical SIM to eSIM when switching or upgrading your phone.
3. Move from eSIM to eSIM when switching or upgrading your phone.

ODT is supported by Apple phones on iPhone 11 and newer running on iOS 26+, and on Samsung devices that are marked as eSIM-enabled.

To check if your device is compatible, go to:

Settings → Connections/Mobile Services → SIM Manager → Add eSIM

If Add eSIM is not available, then you’ll need to activate your eSIM by QR code.
 

Frequently asked questions

Can I use an eSIM and physical SIM together?

Yes, if your phone supports dual SIM, you can use both an eSIM and physical SIM in the same phone.

What is dual SIM?

Dual SIM is when a phone is designed to support two separate SIMs. Traditionally, phones with dual SIM could house two physical SIMs at once and the user could switch between them.

Today, dual SIM phones can support two physical SIMs or a physical SIM and an eSIM. To learn if your phone supports dual SIM, check out our device guides. Simply search for your phone’s make and model.

Can I use an eSIM when travelling?

Yes, in fact, using an eSIM while travelling is a great idea. Using an eSIM from a local network while travelling means that you can avoid roaming charges for your international usage.

There are other benefits too. Using an eSIM allows you to have two profiles active, meaning you can have your existing number and an international number active at the same time.

If you’re travelling to Ireland and are looking to get an Irish eSIM while you’re here, have a look at our phone plans for tourists. These plans are designed specifically for those travelling and include eSIM plans.