Mobile phone eSims explained: what is an eSim and how does it work?

A Sim is an essential part of your mobile contract - telling your phone which mobile network it is connected to, and what your phone number is. Since the early 1990s, Sim cards have been a physical object you insert into a phone. 

However, there is an alternative. eSims launched in 2016 to little fanfare and have struggled to really take off, but are now starting to gain popularity. The GSMA, a trade association for mobile networks across the world, predicts that by 2025, 35% of smartphones will use them, so what are the benefits, and is it worth replacing a physical Sim card? Read on for more. 

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What is an eSim?

Sim cards have progressed from Mini Sim in 1996, to Micro Sim in 2003, to Nano Sim in 2012, with the physical size of the card getting smaller each time. In 2016, the first eSim was launched, in a Samsung Gear S2 smart watch. 

An eSim effectively acts as a virtual Sim card that's built into the phone, and is occasionally referred to by its technical name, eUICC (Embedded Universal Circuit Card). An eSim can be connected to any mobile network that offers eSim services.

New smartphones, tablets and laptops increasingly come with eSim capabilities. 

An eSim shouldn’t have any impact on network performance or signal strength compared to a physical Sim, but it’s good to know which provider has good coverage. You can find out the mobile networks have the best signal in your area with a mobile coverage guide.

How does an eSim work?

Instead of removing a physical Sim card and inserting a new one when you want to change mobile network, you download an eSim profile. This is done by either an app or scanning a QR code. 

You then pick an eSim plan and can start using it immediately, as the relevant information from the network will be installed directly to your phone. It’s possible to have both a physical Sim and an eSim. You can swap between the different networks on each Sim by going to your phone settings:

• Apple devices: Mobile data - Data Plans.
• Samsung devices: Connections - Sim Card Manager.

It’s also possible to store more than one eSim profile at the same time, but you can only be actively using one.

We spoke to Kathiravan Kandasamy, VP of Product Management at Syniverse, a company that produces software and systems for mobile networks. He explained why eSims being installed directly to your phone brings additional security benefits: 'As a digital version of a physical Sim integrated into your phone, an eSIM cannot be physically removed from your device and used in another device. If the device is lost, the eSim can be disabled remotely, ensuring your device is not accessed by unauthorized users.' 

Changing your mobile provider is easier than ever. Find out more in our guide on how to switch mobile provider. Or if you're in the market for a new handset, our mobile phone reviews highlight great value models for under £200.

What are the benefits of eSims?

There are a variety of benefits to using an eSim, particularly if you travel a lot or use different Sim plans:

• Convenience: There's no need to go to a store or wait for a Sim card to be sent to you when you want to change network.
• Flexibility: You can maintain multiple eSim profiles, each with different numbers, and switch to the appropriate Sim for different contexts, such as for work or travel abroad. This could be particularly useful while roaming, allowing you to switch to a local network, or a provider that offers better roaming fees at your destination.
• Coverage: Swap to a network with better coverage if you are in different areas with variable signal strengths frequently.

There are minor downsides to eSims for mobile customers, depending on how you use your Sim plans. An eSim makes it more difficult to swap one plan between multiple devices, as it’s not like a physical Sim card where you can just remove it from a phone and insert it into a different one. If you normally need to do this, you will instead have to go through the eSim activation process each time you want to swap your plan between different phones. 

Overall though, eSims are likely to become increasingly common and provide a better option for consumers than traditional physical Sim cards. 

Kathiravan Kandasamy said: 'Customers can shop online for the eSim options before visiting a holiday or business destination, and purchase the plan online without the need or hassle to look for a physical SIM upon arriving at the destination. Typically, many devices allows for multiple eSims to be used – so you can have multiple networks loaded on your phone, like my home phone number as well as a travel plan. This allows users to receive phone calls or SMS messages like normal when traveling. It can also allow you to use the travel eSim for data and browsing so that users  won’t have to pay expensive roaming charges when abroad.'

Read our guide on five ways to save while roaming to see how picking the right network could help you cut your bills. 

What UK mobile networks offer eSims?

An eSim won't cost you any more or less than a physical Sim card plan would, but it can be more flexible. The UK networks currently offering eSims are:

• EE
• Giffgaff
• Lycamobile 
• O2 
• Three 
• Vodafone 

Instant setup is available with Lycamobile and Three, with your eSim being activated immediately. With EE, O2 and Three, you will need to insert and activate a physical Sim card first, then activate the eSim to replace it. Other networks don’t currently offer eSims, but some such as Sky Mobile have said they are looking into the possibility. 

For detailed reviews of all aspects of mobile provider performance, read our mobile phone provider reviews.

What mobile phones can use eSims?

You'll also need to make sure your mobile phone is compatible with eSims. The Google Pixel range has had eSim capabilities since 2017 (Pixel 3a and later), the Apple iPhone range since 2018 (iPhone XS and later) and Samsung Galaxy range since 2020 (S20 series and later).

Every iPhone from the iPhone 11 to the iPhone 14, including, Pro, Pro Max and Mini versions, can use eSims. Similarly, the Samsung Galaxy range from S20 and S23, including Note and Z Flip versions, are able to use eSims. 

The first eSim-only device was the Motorola Razr, which does not support physical Sim cards at all. 

For advice on what phone to purchase to suit your needs, read our guide to the best smartphones.

What is the future of eSims?

eSims have been available since 2016, but consumer usage and awareness isn’t particularly strong, but uptake should increase over the coming years. We asked Kathiravan Kandasamy for his industry insight on why. He said: 'The adoption of eSims by all major device manufacturers, as well as the recent move to only support eSim form on their devices, will be a catalyst for consumers. Starting with flagship phones, this form will be rolled out to all devices and coupled with eSim management platforms, and the return to travel, will increase eSIM adoption as well.'

Kandasamy continued: 'According to a report by GSMA Intelligence, about 76% of all smartphones will be using eSims by 2030. In the next few years, as more and more devices support eSim, we can see major mobile device markets like India and China also supporting eSims. This will force operators to make major shifts in their customers' digital experience, procurement, and plan management capabilities.  In the near term, we will see more device manufacturers launching eSIM-only devices, as well as dual-form devices (eSIM and Physical SIM).'

Can't decide which mobile network to switch to? Read our guide to the best and worst UK mobile networks, to find how the different providers ranked in our latest survey.