eSIM Explained: How It Works and How to Switch

An eSIM is a rewritable SIM built into a compatible phone and is the digital replacement for the removable plastic SIM card, not a different type of mobile service. Your network downloads a secure profile that identifies your account. Once activated, the line can make calls, receive texts and use mobile data in the same way as a physical SIM on the same plan and network.

The practical gain is that you can activate or move a supported line without waiting for a card in the post. Many compatible phones can also store several profiles and run two lines at once. That can keep work and personal numbers on one phone, or keep a UK number available for calls and security codes while a separate travel eSIM handles data abroad. The exact number of stored and active profiles depends on the handset.

How an eSIM works

SIM stands for Subscriber Identity Module. A SIM holds the credentials used to authenticate a subscription with a mobile network. With a physical SIM, those credentials are stored on a removable chip. With an eSIM, the embedded chip remains in the device and an operator profile is installed remotely under the GSMA's consumer eSIM specification.

1. You choose an eligible plan. The mobile provider links an eSIM profile to your order or existing account.
2. The profile reaches the phone securely. This may happen through the provider's app, a one-use QR code, an activation link or a supported phone-to-phone transfer.
3. The phone downloads it over Wi-Fi or mobile data. The profile is stored on the embedded SIM hardware.
4. You label and activate the line. On a dual-SIM phone, you also choose which line handles calls, messages and mobile data.
5. The network authenticates the subscription. From then on, the eSIM line behaves like the equivalent physical SIM plan.

An eSIM does not inherently improve signal, speed or coverage. Those still depend on the mobile network, local mast capacity, radio bands, handset and plan. Changing the SIM format while staying on the same network and tariff should not create a stronger signal.

Does my phone support eSIM?

Check the phone itself before relying on a model-family list, because regional variants and network software can differ. On an iPhone, open Settings, Mobile Service and look for Add eSIM. On a Pixel, open Settings, Network and Internet, SIMs and look for Add SIM. Samsung normally places the option under Settings, Connections, SIM manager.

Apple's UK support and Google's Pixel help pages maintain model and setup guidance. Older devices, imported variants and some network-supplied models can be exceptions, so use the manufacturer's page and the chosen network's compatibility checker together.

eSIM versus physical SIM

We would choose eSIM for a compatible everyday phone if the network offers a clear self-service replacement route. We would keep a physical SIM where the line must move quickly between several devices, or where access to the provider account and reliable Wi-Fi during recovery cannot be assumed.

Which UK providers support eSIM?

All four UK mobile network operators, EE, O2, Three and Vodafone, publish consumer eSIM support. Several virtual networks also offer it, but availability is not a permanent yes-or-no fact across every product. A provider may support phones but not watches, new customers but not every existing tariff, or pay monthly but only selected pay-as-you-go routes.

As checked on 15 September 2026, EE offers eSIM with eligible pay-monthly devices and SIM-only orders; O2 states support for eligible Pay Monthly, SIM Only and Pay As You Go customers; Three offers eSIM with Three Your Way plans and replacement routes in My3 or its app; and Vodafone offers all SIM-only plans as eSIM plus Pay as you go Plus. Recheck the provider's official eligibility page at checkout because these product rules can change.

If an eSIM is part of a combined home and mobile offer, compare the two contracts separately before linking them. Our UK broadband and mobile bundle guide explains how EE One, Vodafone Together and Virgin Media O2 Volt eligibility can affect the overall saving.

How to set up an eSIM safely

1. Check compatibility and unlock status. Confirm the exact handset, software version, network and plan before paying.
2. Keep the current line active. You may need it to receive an account security code. Do not delete its profile at the start.
3. Connect to trusted Wi-Fi. Charge the phone, install current software and display a QR code on a second screen if that is the provider's method.
4. Add the mobile plan. On iPhone use Settings, Mobile Service, Add eSIM. On Pixel use Settings, Network and Internet, SIMs, Add SIM, Set up an eSIM. Samsung wording varies by model.
5. Name each line. Labels such as Personal, Work or Travel reduce the chance of choosing the wrong data connection.
6. Set the defaults deliberately. Choose the line for calls, texts and mobile data. Turn off data switching if you do not want the phone to use the other line automatically.
7. Test before deleting anything. Make a call, send a text, receive a security code and use mobile data with Wi-Fi switched off.

A provider QR code may be single-use. Do not post it, forward it casually or throw away the old activation information until setup succeeds. If activation fails, stop repeated scans and follow the provider's replacement process. Deleting a profile does not necessarily cancel the contract, and cancelling a contract is not the same action as removing an eSIM from a phone.

How to switch your number to an eSIM

Changing from a physical SIM to an eSIM on the same network is normally a SIM replacement, not a mobile-provider switch. Use the provider's app, online account, device conversion option or support route. Your existing number and tariff should move to the new profile once the replacement activates, but confirm this in the order summary.

When moving to a different UK network, first order an eligible eSIM plan. Use a PAC if you want to keep the number or a STAC if you want the old number closed without porting it. The new provider handles the number transfer after receiving the code. Keep the old line and eSIM profile until the transfer completes, then test incoming calls and texts because number ports can finish at a different time from initial eSIM activation.

Mobile number porting is separate from changing a fixed connection. If you are also moving your home service, our UK broadband switching guide explains One Touch Switch, exit charges and how to avoid cancelling the old broadband too early.

Moving the same eSIM to a new phone depends on both devices and the network. Apple Quick Transfer and supported Android transfers can move a line during device setup, while other cases require a replacement profile. Backing up the phone does not guarantee that the mobile plan itself will restore, so check the network's transfer instructions before wiping or trading in the old handset.

Using an eSIM for travel

A travel eSIM is usually a separate short-term plan downloaded before or during a trip. Many are data-only, so they do not replace the UK phone number for ordinary calls and SMS. A dual-SIM handset can keep the UK line on for incoming calls or security texts while directing mobile data through the travel plan.

Check the destination network, data allowance, validity start, tethering rules, local phone-number inclusion and support route before buying. Some plans begin when installed; others begin only when they first connect abroad. To avoid an unexpected UK-network roaming bill, select the travel eSIM for mobile data, disable data roaming on the UK line and check whether receiving calls or texts abroad carries a charge. The independent MoneySavingExpert guide also warns that activation policies and roaming settings differ between travel eSIM providers.

Common eSIM problems and recovery steps

• No Add eSIM option: update the phone, confirm the regional model and check that the network has not restricted the device.
• QR code will not scan: increase the brightness on the second screen, try manual activation details if supplied, or request a replacement rather than sharing the code.
• Profile installed but no service: restart the phone, confirm the line is switched on, choose it for mobile data and check the provider's activation status.
• Calls work but data does not: verify the selected data line, roaming setting where required and any provider APN instructions.
• Old phone unavailable: secure the lost device and account, then ask the network for a replacement eSIM. Do not assume a cloud backup contains an active network profile.

Use the mobile provider's official support route for activation and account recovery. Apple, Google and Samsung can explain handset settings, but only the network can issue or replace the subscriber profile.