TL;DR
- An eSIM (embedded SIM) is a chip soldered into your device that stores operator profile data digitally; no physical card slot is required.
- You activate an eSIM either by scanning a QR code provided by your operator or by entering an activation code directly in your device settings.
- Most flagship smartphones released from around 2018 onwards support eSIM; many recent models are eSIM-only with no physical SIM tray.
- eSIM and physical SIM can coexist in the same device, enabling two active numbers simultaneously — useful for separating personal and work lines.
- Ofcom supports eSIM as a pro-consumer technology because it lowers switching friction; operators must allow eSIM transfers within the same porting timescales as physical SIMs.
From removable card to embedded chip
The physical SIM card has been a fixture of mobile devices since the early 1990s, but its form has always been a constraint. Every network change required a new card; international travel required swapping hardware; dual-number use required a second slot. The embedded SIM — eSIM — resolves these constraints by replacing the removable plastic card with a chip soldered to the device’s motherboard. That chip can be reprogrammed over the air to store different operator profiles, making network changes a software operation rather than a hardware one.
The technical specification governing eSIM is maintained by the GSMA, the industry body that represents mobile network operators globally. The GSMA’s SGP.22 standard defines the Remote SIM Provisioning architecture for consumer devices, setting out how profiles are downloaded, how security is maintained, and how transfers between operators are handled. UK operators have supported eSIM provisioning for consumer devices since the late 2010s, with uptake accelerating as eSIM-capable handsets became mainstream.
How eSIM provisioning works technically
An eSIM chip contains a secure element — a tamper-resistant microcontroller — that stores operator profiles. Each profile contains the equivalent of what a physical SIM card holds: authentication credentials, network identifiers, and service parameters. When you sign up for a plan on an operator that supports eSIM, the operator generates a profile and makes it available on a Subscription Manager Data Preparation (SM-DP+) server. Your device connects to that server — either by scanning a QR code or entering an activation code — downloads the profile, and installs it in the secure element.
The process is governed by GSMA SGP.22 technical specifications and uses mutual authentication between device and server to prevent unauthorised profile downloads. A single eSIM chip can store multiple profiles simultaneously, though only one (or, on dual-SIM devices, two) can be active at a time. Profiles can be switched in software, deleted, or reinstalled without any physical action required. This architecture is what makes eSIM genuinely different from previous “soft SIM” concepts: the secure element provides the same level of fraud resistance as a physical SIM card.
| Feature | Physical SIM | eSIM |
|---|---|---|
| Form factor | Removable plastic card (nano-SIM most common) | Chip soldered to device motherboard |
| Activation method | Insert card physically | Scan QR code or enter activation code in settings |
| Network switching | Requires new physical card from new operator | Profile download over the air; no hardware needed |
| Multiple profiles | One profile per card; second number needs second slot | Multiple profiles stored; switch in software |
| Device space | Requires physical tray taking internal space | No tray needed; frees space for battery or waterproofing |
| Security standard | ETSI physical SIM standards | GSMA SGP.22 Remote SIM Provisioning |
Which devices support eSIM in the UK
eSIM support has expanded substantially since Apple introduced it in the iPhone XS and XS Max in 2018. As of 2026, all current iPhone models support eSIM; the iPhone 14 series launched in the US as eSIM-only, and UK models retained a physical SIM slot alongside eSIM. Recent Samsung Galaxy flagship and mid-range models support eSIM. Google Pixel devices from the Pixel 3a onwards support eSIM. A growing range of Android devices from other manufacturers, including certain models from Motorola and OnePlus, also support eSIM, though coverage is not universal across all price points.
eSIM is also available on a range of non-phone devices. Certain iPad models support eSIM, as do Apple Watch models with cellular capability. Some Windows laptops with integrated LTE or 5G modems support eSIM, and smartwatches from various manufacturers use eSIM for standalone connectivity. Checking the manufacturer’s technical specifications for a specific device model is the only reliable way to confirm eSIM support, as support varies by model variant and market region.
How to activate an eSIM in the UK
The activation process differs slightly between operators but follows the same general sequence. First, you purchase a plan that includes eSIM support — not all tariffs offered by an operator may include eSIM, so confirm at the point of sale. The operator then provides either a QR code (typically emailed or displayed in an account portal) or a manual activation code. On the device, you navigate to Settings, then to Mobile or Cellular, then to Add eSIM or similar, and either scan the QR code or enter the code manually. The device connects to the operator’s SM-DP+ server, downloads the profile, and the eSIM becomes active, usually within a few minutes.
One practical constraint: scanning an eSIM QR code requires a second device or a printed copy, because the phone being activated cannot simultaneously scan a code displayed on its own screen. Operators typically email the QR code, allowing you to scan it from a computer or tablet screen. If you are switching to a new device, your old operator can provide an eSIM transfer QR code for your existing number, subject to any applicable porting process.
Ofcom’s position on eSIM and switching
Ofcom has consistently treated eSIM as a pro-consumer development because it reduces the friction associated with switching mobile providers. Removing the need to wait for a physical SIM to arrive by post accelerates the switching process and lowers the practical barrier to changing operators. Ofcom’s work on the Auto-Switch process, which enables consumers to switch provider without needing to contact their old provider first, complements eSIM’s technical switching capability. Operators are required to support eSIM transfers within the same regulatory timescales as physical SIM porting, meaning a number port via eSIM must complete within one working day once the PAC code process has been initiated.
Consumer data protection in eSIM provisioning falls under the general data protection framework administered by the ICO, as operator profiles contain personal data. The GSMA’s SGP.22 specification includes privacy protections within the provisioning architecture, including controls over which entities can push profile updates.
What this means in practice
Marcus works for a company that provides him with a corporate mobile plan on O2 but he wants a personal number on a different network with better coverage near his home in a semi-rural part of Shropshire. His iPhone supports both a physical SIM and an eSIM. He keeps his work physical SIM in the tray and activates a personal plan via eSIM using the QR code emailed by his chosen personal operator. His phone now displays two signal bars and two network names. He sets his personal number as the default for outgoing calls and his work number as default for messaging. The process takes under ten minutes and requires no hardware changes.
Related Guides
How we verified this
This article draws on GSMA SGP.22 Remote SIM Provisioning technical specifications, Ofcom guidance on mobile switching and the Auto-Switch process, Ofcom’s Connected Nations reports for device and network context, and ICO guidance on data protection in telecoms services.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
What is an eSIM?
An eSIM (embedded SIM) is a programmable chip soldered permanently into a device that performs the same authentication and network-connection functions as a physical SIM card. Instead of inserting a plastic card, you download an operator profile over the air. The chip can hold multiple profiles and switch between them in software, making network changes faster and easier than with a traditional SIM.
Which phones support eSIM in the UK?
All current iPhone models support eSIM, as do Google Pixel devices from the Pixel 3a onwards and a broad range of Samsung Galaxy flagship and mid-range handsets. eSIM support varies among other Android manufacturers; check the manufacturer’s specification page for your specific model. Not all variants of a model may support eSIM — regional versions sometimes differ — so verify your exact device before purchasing an eSIM plan.
How do I activate an eSIM?
Purchase a plan that includes eSIM from your chosen UK operator. The operator will provide a QR code (usually by email) or a manual activation code. Go to Settings → Mobile or Cellular → Add eSIM on your device, then scan the QR code or enter the activation code. The profile downloads over the internet and the eSIM activates within a few minutes. You will need a separate device or printed copy to scan the QR code, as you cannot scan a code on the same screen.
Can I use an eSIM and a physical SIM at the same time?
Yes, on devices that support it. Most flagship smartphones with eSIM capability also retain a physical nano-SIM tray, allowing both to be active simultaneously. This is called a dual SIM, dual standby configuration. Both numbers can receive calls and messages; you typically choose a default for outgoing calls and data, with the option to switch manually. Check your specific device specifications, as some eSIM-only models (common in the US market) lack a physical tray.
Can I transfer an eSIM to a new phone?
eSIM profiles are tied to a specific device and cannot be physically moved like a plastic card, but you can transfer your number to a new phone’s eSIM. You can do this either by requesting a new eSIM QR code from your operator (which deactivates the old profile) or, on some device ecosystems, by using a device-to-device transfer process. The process must comply with Ofcom’s porting rules, so your number should transfer within one working day once initiated.
