What Is eUICC and How It Works for IoT Devices

As IoT modules start to include embedded SIM technology (eSIM), there's a lot of confusion around terminology. Most people assume that an eSIM denotes over-the-air (OTA) profile provisioning. But eSIM hardware does not provide that capability. It's the embedded universal integrated circuit card (eUICC) that makes OTA provisioning possible.

Contrary to popular belief, eUICC does not only work with eSIM. Many SIM providers, including Hologram, are beginning to offer removable SIM cards equipped with eUICC to allow remote profile provisioning after deployment.

The eUICC represents a huge step forward for cellular connectivity because of the flexibility it creates. It's a piece of software located inside the eSIM chip that allows you to send out and store multiple SIM profiles. Based on the older GSMA standards for UICC, it functions much like the software within a physical SIM, with some variations around test specifications (which can't be performed the same way in eUICC-enabled eSIM because the software is internal to the device). And it's considerably larger: while a physical SIM typically has a memory of either 64KB or 128KB, an eUICC can hold at least 512KB of data and support several profiles.

Think of it as a travel passport with multiple visas inside. You can use a different visa each time you enter a new country. If you find yourself in an unexpected country without a visa, you can apply for one, receive it immediately, and go on your way. It's a convenient way to travel. (Your IoT devices will think so, too.)

Key Takeaways

• eUICC is software on a SIM chip that enables over-the-air provisioning and remote switching between multiple carrier profiles, while eSIM refers only to the physical embedded chip.
• The OTA provisioning process uses a bootstrap profile to establish an initial network connection, then a subscription management platform delivers and activates the appropriate carrier profile via SMS.
• eUICC simplifies IoT manufacturing by allowing a single SKU for global deployments, with carrier profiles sent remotely after devices reach the field.
• Working with a carrier-neutral partner helps overcome ecosystem challenges where carriers are still navigating how to share SIM profiles across the eSIM/eUICC landscape.

How does eUICC work?

Before walking through the full process, here are key terms to understand:

• Bootstrap profile: A pre-installed profile at manufacture that enables an initial network connection to download operational profiles.
• OTA gateway and SMS communication: The SMS channel provides the communication route between the SIM card and the cellular network's OTA Gateway.
• SM-DP (Subscription Manager – Data Preparation): Stores profiles and delivers them to the eUICC.
• SM-SR (Subscription Manager – Secure Routing): Manages profile status and ensures secure data transfer.

Step-by-step: How OTA profile provisioning works

Now, imagine you're in the field and have just received a device that's ready to be deployed. What happens when you turn on the device?

Initial connection

First, the eUICC device connects to the server via its bootstrap profile. The bootstrap doesn't allow the device to perform any function other than making a connection to download a profile. Once that initial connection is made, a platform provider on the backend can send out the profile your device needs to function in its current locale.

New profile is enabled

Once the SM-DP completes the download to the eUICC, it's time for the SM-SR to do its thing. As the manager for profile status, the SM-SR can tell the eUICC to disable, enable, or delete a profile. In this case, it enables the new profile.

eUICC talks to device

The eUICC then communicates with the device module to say it's received an SMS and needs to download a profile. The module affirms this action.

New profile downloaded

The profile is fully downloaded onto the device.

Success confirmed

Finally, the eUICC confirms a successful profile installation via SMS. The message is received through the OTA gateway and the profile becomes active. Congratulations, your device is now up and running.

eUICC challenges and the role of a carrier-neutral partner

While eUICC is set for wide IoT adoption, with newer standards like SGP.32 continuing to advance the ecosystem, challenges remain. Carriers are still navigating how to share SIM profiles in the eSIM/eUICC ecosystem. Broader global connectivity will require more carrier agreements.

A carrier-neutral partner like Hologram helps you sidestep these challenges. We continuously onboard new carriers and networks to deliver optimal connectivity for your deployment.

eUICC gives us more flexibility than traditional SIMs ever allowed. Instead of one shot at manufacturing to lock in connectivity, we can now send updates OTA—meaning your connectivity improves over time.

How does eUICC benefit IoT device deployments?

With the mechanics of OTA provisioning in mind, it's easier to see why eUICC is such a meaningful shift for IoT. The same architecture that makes remote profile management possible also unlocks a range of practical advantages for the way devices are built, deployed, and maintained over their lifetime.

Simplifies manufacturing

eUICC lets you send SIM profiles to IoT devices after deployment. This creates several manufacturing advantages:

• Single SKU production: No need to manufacture regional device variants
• Lower inventory costs: One product version serves global deployments
• Faster deployment: Devices go online immediately in the field without waiting for SIM installation

Provides flexibility

eUICC enables profile flexibility throughout a device's lifecycle:

• Remote carrier switching: Provision new profiles without physical access to the device
• Redeployment ready: Swap profiles when devices move to new locations
• Multi-profile storage: Store several profiles and shift between carriers as devices roam

Makes devices future-proof

Profile switching also future-proofs devices against network sunsets and carrier changes. Remote software updates keep devices current with the latest features and carrier offerings with no field recalls required.

In other words, we're constantly adding visas to your passport, giving you more flexibility to roam into new countries and situations around the world and stay connected.