What is an eSim?

9 min Read Published: 07 Jun 2024

What is an eSim?An eSim is built into your phone, rather than inserted like a physical sim card. You can buy a plan online and add it to your handset to manage your calls, texts and data. In this article we explain how an eSim works, how to use one to save money abroad as well as considering the pros and cons of the technology.

What is an eSim?

An eSim is just like a standard sim card, but there is no physical piece of plastic to put into your mobile. The ‘e’ in eSim stands for embedded, because the hardware already exists in your phone, tablet or laptop. Once you buy a package and set it up, the eSim can manage the amount of data, calls and texts that you use – just like a standard sim card. An eSim package can be purchased online and activated in your phone’s settings using a QR or alphanumeric code.

Most new phones, tablets and even laptops in the UK have eSim capabilities and using one shouldn’t affect the performance of your device. Standard sim cards are still dominant in the UK, but eSims have some important features that can make them very useful in certain circumstances, such as roaming abroad.

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What mobile phones can use eSims?

You will need to have a mobile phone with an eSim capability to buy a package and use the functionality. Generally, you will be okay if you have a Google phone from 2017 onwards, an iPhone from 2018 onwards or a Samsung Galaxy from 2020 onwards. Here is a full list of all the eSim compatible devices from the major mobile manufacturers.

Compatible iPhone models Compatible Google models Compatible Samsung models
iPhone XR Google Pixel 2 (and XL) Samsung Galaxy S20 (and Ultra)
iPhone XS Google Pixel 3 (and XL) Samsung Galaxy S20+ (and 5g)
iPhone XS Max Google Pixel 3a (and XL) Samsung Galaxy S21
Google Pixel 4 (and XL) Samsung Galaxy S21+ (5G and Ultra 5G)
iPhone 11 (and Pro) Google Pixel 4a Samsung Galaxy S22 (and Ultra)
Google Pixel 5 Samsung Galaxy S22+
iPhone SE 2 Google Pixel 5a Samsung Galaxy Note 20 (and Ultra 5G)
Samsung Galaxy Fold
iPhone 12 (and Mini, Pro and Pro Max) Google Pixel 6 (and Pro) Samsung Galaxy Z Fold2 5G
Samsung Galaxy Z Fold3 5G
iPhone 13 (and Mini, Pro and Pro Max) Google Pixel 6a Samsung Galaxy Z Fold4
Samsung Galaxy Z Flip
iPhone SE 3 Google Pixel 7 (and Pro) Samsung Galaxy Z Flip3 5G
Samsung Galaxy Z Flip4
iPhone 14 (and Plus, Pro and Pro Max) Google Pixel 8 (and Pro) Samsung Galaxy S23 (and Ultra)
Samsung Galaxy S23+
iPhone 15 (and Plus, Pro and Pro Max) Google Pixel Fold Samsung Galaxy S24 (and Ultra)
Samsung Galaxy S24+

You can also use an eSim package with Samsung Gear S2 and Gear S3 smartwatches, the Samsung's Galaxy Tab S9 5G tablet, the Apple Watch Series 3, 4 and 5, and most new iPads.

New Motorola phones (such as the Edge+, Razr, Razr+, OnePlus 11 and OnePlus Open) also support eSIM.

How does an eSim work?

An eSim is a small chip integrated into your phone. You can activate a plan from a range of domestic and international mobile networks onto the chip, allowing it to function just as a plastic sim card would.

You can store multiple plans on your phone through your eSim, though you can usually only actively use one at a time. Switching between them in your phone’s setting is easy and allows you to make the most of the different plans you have available. It saves you having to remove one card and insert another to use a different network or access a different data plan. You can also set your eSim to manage your data, but your physical sim to manage your calls and texts. This means you can avoid losing your number if you get an eSim for roaming abroad.

You can buy an international eSim from the comfort of your own home before you travel abroad. This is a much easier alternative to trying to find a local phone shop and buying a physical sim card when you go on holiday, and usually much cheaper than paying roaming costs if you are travelling beyond Europe.

How to use an eSim for roaming

One of the key features of an eSim is that you can buy a local data package to save you money when you use your phone abroad. The cost savings can be significant if you are travelling beyond Europe and the set-up process is very straightforward. Many UK providers still offer free roaming in European countries, so an eSim may be unnecessary unless you are going further afield.

Here is a step-by-step guide on how to purchase and activate an eSim:

1) Pick your eSim

There are a lot of different eSims available for most destinations, but the majority of plans are data-only. This will not be a problem for most mobile users as you can still make calls and send messages through online services such as WhatsApp or Messenger.

You should look for a plan that offers you the package you need for the duration of your stay. For example, if you usually use 5GB of data a month, a 3 GB plan is likely to be more than enough for a two-week holiday. However, it is also worth thinking about how you will use your phone while you are away. Will there be Wi-Fi at your hotel or resort? Will you be streaming videos using data, or just using maps to navigate around?

If you are buying your eSim in a foreign currency, make sure to use a card that will not charge you fees. You should also think about when you want your plan to start.

Once the purchase is complete, you should get an email explaining how to download and install the plan.

2) Set up your eSim

Setting up your eSim is easy and most providers will send you an email explaining how to do so. You should ensure that your new eSim is the default option for data and that you have allowed data roaming via your eSim (not for your usual sim).

Keep your usual sim as the default for calls. This way you can still receive calls to your number in an emergency, though the person calling may get a hefty bill if you pick up.

3) Stick to online messaging and calling services

Messaging, voice calling or video calling through WhatsApp, Gmail, Messenger or any other online service uses data rather than minutes or texts. This should be your default choice for contacting anyone when using your eSim, otherwise you could be hit with hefty roaming charges.

Pros and cons of eSims

Here are the key pros and cons of eSims that you should consider:

Pros of eSims

Cons of eSims

Easy to set up All you need to do is scan a QR code or enter an alphanumeric code to get your eSim up and running. Difficult to move a plan to a different device A physical sim card can be removed and put into a different phone, tablet or smartwatch, but an eSim cannot. Instead, you will have to register it with the new device and go through the setup process again.
Easy to switch between networks You can move to a new network at the end of your existing contract without having to wait for a new sim to arrive or going to a shop to buy one. You also don’t need to remove the physical sim card from your phone.
Switch between multiple sims You can have more than one plan stored on your phone and switch between them easily. This could be because you want to use one number for work and another for personal calls, but keep the same handset. If you are a regular traveller, you could also have one plan with 20GB of data in the USA and one plan with 20GB of data in the UK, then switch between the two depending on which country you are in. Limited range of deals The major UK mobile networks all offer eSim packages, but there is not the same range of deals that UK mobile customers are used to. This is because many of the smaller companies only offer physical sim cards.
No need to buy a sim card when you are abroad You can purchase an international eSim from the comfort of your own home, rather than trying to find a phone shop in a new country when you arrive.
Avoid roaming charges You can avoid roaming charges by purchasing an international eSim that charges you like a local and costs you less than roaming add-ons and sim cards aimed at tourists. Sometimes you need a physical sim card too EE, O2 and Three require you to buy a physical sim card, activate it, then set up your eSim. This takes away a lot of the convenience and flexibility of getting an eSim.
You can keep your number while you are abroad You can manage calls through your usual sim card – meaning you will keep your number – but manage data through your international eSim package. This means you can still be reached in an emergency and get the cost benefits of an eSim.
Get better coverage You could get a plan with one network that offers very little coverage at home, but a great signal at work and a second plan that is the opposite. You could then switch between your plans to maximise your coverage wherever you are. Not all handsets are compatible You will likely need to have a relatively new handset to use an eSim, as older phones will not have the hardware built in.
Dual-sim capability Most devices only support one plan at a time, but a few phones (currently iPhone 13, 14 and 15 models for example) offer what is called dual-sim. This allows you to have two active plans at the same time – and two numbers – without having to switch between the two.

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What UK companies offer eSims?

There are few UK providers that offer eSim plans, but not as many options as you will find in other countries. At the time of writing, EE, O2, Three and Vodafone all offer an eSim pay-monthly plan, while Lycamobile offers both a pay-monthly and pay-as-you-go option.

Unfortunately, EE, O2 and Three require you to activate a physical sim card before you can set up your eSim, which cuts into one of the major advantages of having an eSim in the first place – convenience.

There is a suggestion that other major UK providers will be offering eSims soon, but currently the range of choice is very limited.

Which mobile networks support eSim?

While only a few UK providers offer eSim plans, they do cover the majority of the UK’s mobile infrastructure. EE, O2, Three and Vodafone all support eSim with the lack of customer choice caused by smaller companies being slow to the market. However, most small UK providers power their plans through a partnership with either EE, O2, Three and Vodafone, so all major networks are available, just without the range of deals that customers can get with a physical sim card.

Can eSIMs support multiple networks at the same time?

An eSim can support multiple mobile subscription packages, but you can usually only use one at a time with the exception of iPhone 13, 14 and 15 models. However, on most phones it is very easy to switch between packages to maximise the benefits of your multiple plans. For example, you could use one eSim for your calls, then switch to another to do anything that would use up data. This is particularly useful if you are on holiday and looking to avoid hefty data roaming charges.

Should I get a phone with an eSim?

Most new phones include the hardware to add an eSim package, but it is probably not a feature worth buying a new phone for if you are happy with your current one. The benefits of an eSim over a standard plastic sim card for day-to-day use are not particularly significant in the UK. Even if you are a regular traveller to Europe, you are likely to be covered by most – though not all – major UK plans.

If you are heading to the USA, India or other parts of North America or Asia regularly, an eSim-compatible phone would be very useful. This is because you can purchase a local eSim before you leave home that can cover your data usage for a fraction of the cost of paying your UK provider’s international rates.

For example, O2 customers travelling to the USA can pay £6 per day for unlimited data, texts and minutes with the O2 Travel Bolt On. Alternatively, they could purchase a 30-day local USA eSim with 20GB data for 21 USD (£16.63). The O2 option is £6 per day, the eSim route is around 55p per day. This example assumes you will not need to make calls or texts and that 20GB is more than enough for most travellers, but it gives you an idea of how an eSim can be great value when you are abroad. Whether that is enough of a justification to swap your current phone for a new one will depend on your lifestyle.

Will all phones have eSims in the future?

With so many new phones now supporting eSim packages, it seems only a matter of time until they overtake the plastic sim card. The major phone providers – most notably Apple, Google and Samsung – have done their part by building handsets with eSim compatible hardware. In the US, some iPhones do not even support physical sim cards anymore. However, the phone itself is only half the story, as it will take more of the UK’s mobile networks offering attractive eSim packages to fully render the physical sim card obsolete.



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