What is eUICC? – IoT Uncovered

Lucy Holden Senior Marketing Executive

Lucy is passionate about how IoT is used for the greater good to change the world and save lives.

In our past blog, we explored how multi-IMSI SIMs provide a secure solution for multi-regional IoT deployments, where expensive roaming issues can play havoc. This week we’re here to talk about the successor to multi-IMSI SIMs – the GSMA standards-based eUICC or eSIM – and unpack its capabilities, potential and challenges.

Key requirements for an IoT SIM

As we touched on in the last blog, the SIM in an IoT device has a critical job to ensure secure, reliable connectivity between the device and the enterprise data centre. Zero-touch connectivity starts when the device is installed and continues until the end of its lifespan.

At the start of any IoT project, it’s important to forecast how long the device should operate in the field. The SIM needs to be robust enough to last the lifetime of its paired device. And it should be able to receive over-the-air commands to update software and security or change networks. That’s a big ask – and not many SIMs can do it.

The SIM might stay connected to one mobile network or roam onto others. It might need to change networks to achieve better connectivity or avoid roaming restrictions. And that’s where multi-IMSI SIMs come into their own – housing multiple mobile network operator profiles on a single SIM, eradicating the need to physically swap SIM cards or enter new network information. So, how is eUICC different?

eUICC – fit for consumer mobile but what about IoT?

In order to solve the historically painful process for mobile phone customers changing network suppliers, the GSMA introduced the eUICC specification to enable users to change their network provider without physically swapping the SIM card.

The over-the-air capability to swap providers means eUICC should be ideal for IoT devices, which may be inaccessible or have embedded SIMs (or both).

But in practice, eUICC for IoT is complicated by both technical and commercial issues.

When a consumer wants to swap network providers using eUICC, they can connect their device to Wi-Fi so the new provider can download their profile to the SIM.

Yet most IoT devices don’t have a user interface, access to Wi-Fi connectivity or a user to operate the device. This means both current and new providers must cooperate to make the swap.

A network provider who wants to support eUICC must provide:

  • eUICC-compliant SIMs that can be remotely provisioned
  • A Remote SIM Provisioning Platform (RSP)

The RSP is comprised of two elements:

  • SM-DP (Subscription Manager-Data Preparation) stores and manages the network profiles
  • SM-SR (Subscription Manager-Secure Routing) handles secure communications with the eUICC SIMs, enabling the SIMs to be provisioned remotely

A swap between two providers also requires a deep technical integration between their systems – at the SM-SR level. An integration of this type can cost hundreds and thousands of pounds and take months to implement. It also demands specific development expertise which can be difficult to find.

With around 700 network operators globally, most operators are unlikely to have integrations with many of the other network providers. Some don’t support eUICC at all.

Network transfers on standard eUICC take time to agree and implement. If you’re changing providers because of poor IoT connectivity, time is something you don’t have. The new provider is responsible for delivering the connectivity service – that means a new contract, a new management platform, a new support system.

If you have multiple providers for your devices, you’ll have multiple contracts, management platforms and support systems. You may still have contracts with previous providers, if their contracts hadn’t expired before you swapped.

And what if the new IMSI fails to connect in some locations?

When the new provider takes over, the previous provider’s IMSIs are removed from the SIMs. So, if the new IMSI fails to connect, there’s no way back…the devices remain disconnected until someone can physically sort them out.

So, is there any point having eUICC-compliant SIMs for IoT?

eUICC is useful for enterprises with hundreds of thousands of devices. They have the buying power and resources to change network providers at regular intervals to achieve better deals.

For smaller businesses, using eUICC to switch providers isn’t usually a realistic option today. But future technical and commercial developments may create more cost-effective and practical solutions.

Given the long lifespan of IoT devices, it’s sensible to use eUICC-compliant SIMs so you can take advantage of any future network changes or market opportunities.

However, there are customized, advanced eUICC solutions available from providers such as Eseye that harness the benefits of eUICC in a useable way for commercial IoT. Providers who invest in the infrastructure and expertise required to meet the eUICC specification – both the SIM and the RSP (in particular the SM-SR functionality) – show they’re serious about offering the future-proofed solutions that IoT businesses need. This is an area that Eseye has been investing in for several years, building on their extensive multi-IMSI SIM capability.

So, if that’s you and your business is focusing on the future and not just the now, read the next IoT Uncovered blog which outlines the evolutionary development from Eseye that delivers on the promise of eUICC for IoT.


IMSI: International Mobile Subscriber Identifier – it identifies the user on the network. A traditional SIM contains one network profile with one IMSI. This IMSI is tied to a single network provider.

Multi-IMSI SIM: contains multiple IMSIs, each of which can connect to a different network. There is usually one bootstrap IMSI that comes pre-loaded, although more advanced SIMs can accommodate multiple bootstraps, and some SIMs can be updated with additional IMSIs over-the-air.

eSIM: used to mean a SIM that was embedded in a device. It’s now used interchangeably with eUICC.

eUICC: stands for embedded Universal Integrated Circuit Card. An eUICC SIM is installed in a device, either as an embedded chip or in the traditional removable form. It can store multiple network profiles and being provisioned remotely.

SIM: Subscriber Identity Module and contains the credentials for accessing a network.

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