What is an eUICC?
An eUICC is the SIM (subscriber identity module) architecture that lets a compatible device download, store, and switch between multiple carrier profiles over the air. Saily is a consumer example — its prepaid travel eSIM lets you install a mobile data profile in-app, with no physical SIM to swap out, so you can stay connected abroad with affordable data in 200+ destinations.
GSMA (GSM Association) specifications define eUICC technology for consumer, machine-to-machine (M2M), and IoT use cases. The term “eUICC” describes the underlying capability, while “eSIM” is the term phone makers and travelers use for the technology in everyday life. See our full explanation of what an eSIM is and our guide to eSIM-related terms for more on how it works.
💡 Good to know: The GSMA, or GSM Association, is the industry organization that develops specifications and standards for mobile technologies, including eSIM and eUICC.
eSIM vs. eUICC: What’s the difference?
The difference between an eSIM and an eUICC mostly comes down to terminology. An eUICC is the secure chip that stores and manages downloadable carrier profiles. eSIM is the broader, consumer-facing term — it can refer to the chip itself or to the remote SIM provisioning technology built on top of it. That’s why “eSIM” tends to cover both the hardware and the system in everyday use, while “eUICC” stays strictly technical, referring to the component underneath.
Not every SIM chip built into a device supports eUICC functionality. Some IoT devices, for example, use fixed embedded SIMs locked to a single carrier, with no way to download or switch profiles remotely. Travel eSIM services, on the other hand, rely on eUICC technology — that’s what makes it possible to download a new profile without ever inserting a physical SIM. Curious how eSIMs compare to physical SIMs? Read more about the difference between eSIMs vs. nano SIMs.
| eUICC | eSIM (consumer use) | Removable UICC (plastic SIM) |
|---|
What it is | Secure hardware and software that supports remote SIM provisioning | The common term for SIM service delivered through remote provisioning, usually using a built-in eUICC | A physical SIM card inserted into a SIM tray |
|---|
Number of carrier profiles | Can store multiple profiles | Can store multiple profiles when using an eUICC | Usually one subscription per card |
|---|
Adding a new carrier | Download a profile over the air | Download a profile over the air | Replace the physical card |
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Form factor | Can be removable or non-removable | Usually non-removable in consumer phones | Removable |
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Identifier | EID (32-digit number) identifies the eUICC — each profile also has an ICCID (Integrated Circuit Card Identifier) | EID for the eUICC and ICCID for individual profiles | ICCID |
|---|
Typical devices | Phones, IoT modules, connected cars, smart meters | Phones, tablets, smartwatches, laptops | Older handsets, basic phones, routers |
|---|
💡 Good to know: Because an eSIM profile is stored digitally, a factory reset can erase it along with your data. That doesn’t cancel your plan — but you’d have to set the eSIM up again before you can use it. On an iPhone, you can choose to keep your eSIM while erasing data, which saves you the hassle of reactivating it after the reset.
How does eUICC remote SIM provisioning work?
eUICC works through remote SIM provisioning, which allows a carrier profile to be downloaded over an internet or cellular connection and installed on the eUICC without physically replacing the SIM card.
Getting an eSIM profile onto your smartphone typically involves four steps:
You order a profile. You choose a mobile plan from a carrier or provider.
The profile is prepared. A secure SM-DP+ server prepares the carrier profile and makes it available for download.
You download it on your device. The profile is securely transferred to the eUICC and installed.
The profile is enabled. Your device can use the installed profile to connect to the carrier’s network. And because the eUICC can store multiple profiles, switching carriers later doesn’t mean replacing any hardware — you just disable one profile and activate another.
The eUICC keeps the same unique EID as profiles are added, removed, enabled, or disabled. In other words, the EID identifies the eUICC, while the carrier profiles stored on the chip can change.
Provisioning works differently depending on the device. With a consumer eSIM, you typically initiate the installation yourself. Saily, for example, lets you install an eSIM directly in the app, with no QR code to scan or activation code to type in.
Machine-to-machine (M2M) systems — think connected cars, smart meters, or industrial sensors — are designed for remote management instead. They let mobile network operators or service providers provision and manage profiles across large fleets of devices, without anyone physically handling each one.
💡 Good to know: The GSMA has separate remote SIM provisioning specifications for different use cases. SGP.22 covers consumer devices such as smartphones and tablets, SGP.02 was developed for M2M deployments, and SGP.32 is designed specifically for IoT devices, including those with limited power or user interfaces.
What is an EID, and where can you find it?
The EID is the 32-digit identifier permanently assigned to an eUICC. On iPhones that support eSIM technology, you can find the EID under “Settings” > “General” > “About.” On a Google Pixel, go to “Settings” > “About phone” > “SIM status.” The path may differ on other Android devices.
The EID identifies the eUICC itself, while the Integrated Circuit Card ID (ICCID) identifies an individual carrier profile stored on it. Your EID stays the same when you add, remove, or switch carrier profiles, and a carrier or eSIM service provider may ask for it when troubleshooting activation or connectivity problems. If an EID appears in your phone’s settings, that confirms the device has an eUICC that supports remote SIM provisioning.
You can also check Saily’s list of eSIM-supported devices if you’re unsure whether your phone supports eSIM technology.
What is an eUICC solution for IoT and connected devices?
An eUICC solution is a managed connectivity service that lets a business load, switch, and manage carrier profiles remotely across a fleet of connected devices, often through a central management platform. An eUICC SIM card can be remotely provisioned with a local carrier profile after deployment, which can help devices shipped internationally avoid relying on permanent roaming.
Common eUICC deployments include:
Connected cars.
Smart utility meters.
Asset and fleet trackers.
Point-of-sale (POS) terminals.
Industrial sensors and equipment.
Connected medical devices.
Remote provisioning can reduce the need for on-site technician visits by allowing businesses to handle tasks such as switching operator profiles remotely. It can also give businesses more flexibility to change network providers, manufacture a single connectivity-ready device configuration for multiple markets, and move devices to another supported network if an existing carrier or network service is discontinued.
However, eUICC connectivity still comes with some practical considerations. Businesses may pay subscription or platform management fees, hardware and software need to be eUICC compatible, and carrier profiles must support the markets and networks where the fleet will operate. Profile switching should also be tested before a large-scale rollout to make sure everything reconnects and runs as expected.
Which eUICC SIM is best for IoT and connected devices?
The best eUICC SIM for connected devices supports the appropriate GSMA remote provisioning standard, works with the networks and technologies your global deployment needs, and can handle the conditions where the hardware will operate. Depending on the use case, that may mean an industrial-grade MFF2 eUICC — a form factor (physical design) where the chip is soldered permanently into the device — or a removable format that still supports remote profile management.
When comparing the best eUICC SIM options for an IoT fleet, consider:
SIM form factor. Check the physical format the deployment requires, such as an MFF2 eUICC soldered directly to the device or a removable 4FF nano SIM.
Temperature and durability rating. Devices used outdoors, in vehicles, or in industrial environments may need components rated for extreme temperatures, vibration, and other harsh conditions.
Profile capacity. Check how many operator profiles the eUICC can store and manage.
Network support. Make sure the hardware and connectivity service support the technologies you need, such as LTE-M, NB-IoT, 4G, or 5G.
API access. For large fleets, APIs can make it easier to provision profiles, monitor devices, and integrate connectivity management with other systems.
Management costs. Compare platform fees and per-device pricing as well as the cost of mobile data.
The most reliable eUICC SIM isn’t necessarily the one with the strongest signal in one location. For a large deployment, look for access to multiple carrier networks, service-level agreements (SLAs) that match your uptime requirements, and safeguards if a profile change interrupts connectivity. SGP.32, for example, includes a rollback mechanism that can return a device to its previously enabled profile when a profile switch causes a connectivity failure.
How does eUICC technology apply to travelers looking for global connectivity?
eUICC makes it possible to download a travel eSIM and switch mobile data plans without changing a physical SIM card. For travelers who need reliable connectivity on a smartphone, tablet, or other mobile devices, that usually means choosing a consumer eSIM rather than an IoT eUICC service. Saily offers affordable data plans with in-app eSIM installation and 24/7 live chat support.
