Dynamic eUICCs vs Static UICCs

If you think all SIMs are built using the same technology, think again.

“IMSI” stands for International Mobile Subscriber Identities and is a unique number that lets Mobile Network Operators (MNOs) authenticate their subscribers so they can access a specific network. “Multi-IMSI” stands for Multiple International Mobile Subscriber Identities and is mainly designed for dual network and roaming applications. They are, in fact, physical SIMs and even maybe embedded as a faux-eSIM. Unlike traditional “single-IMSI” SIMs, static multi-IMSI’s contain multiple pre-loaded IMSIs or mobile subscriptions.

On the other hand, “eUICC” stands for Embedded Universal Integrated Circuit Card and is also known as an “eSIM.” A true eUICC lets users switch networks over-the-air (OTA) – meaning a device operator can pick its network and dynamically change identities. With eUICC tech, when a device wakes up, an operational profile can be pushed down remotely, meaning the IMSIs stored on the card can change over time and can be assigned from the cloud dynamically.

eUICC and eSIM are terms that are nearly interchangeable with one minor nuanced difference: eUICC refers to the hardware of a programmable chip either in a plastic card tray or embedded form-factor, and eSIM is a more general term describing either an embedded SIM card or the electronic network access credential information downloaded to a device (e.g., downloading an eSIM).

Differences Between Dynamic eUICCs and Static UICCs

With static multi-IMSI solutions, the two or more IMSI credentials installed at the factory are stuck there. If a device goes out of the pre-configured network’s boundaries or scope, the device operator must physically change the SIM to change the state – which, in most cases, is not possible for IoT or M2M applications and devices. On the other hand, with a true eUICC eSIM card, a device operator can dynamically change the SIM profile OTA without replacing the physical SIM, simplifying operations, reducing costs, and ensuring a device is always connected.

Here are some other differences between SIM (static single or multi-IMSI UICC) and eSIM (dynamic or multi-IMSI eUICC) form factors: