What Is the Difference Between eSIM and eUICC?

eUICC and eSIM: are they the same thing? One would be forgiven for thinking that eUICC and eSIM are the same things, given that they are being used interchangeably by many media sites and blogs. The reality is, however, that they are two different technologies.

This article will define what eSIM and eUICC are talk about the different benefits of each.

What Is eSIM?

SIM stands for Subscriber Identity Module and is often used to refer to the small card-shaped chip that is inserted into smartphones and other mobile-connected devices. The SIM enables a device to be recognized on the carrier network and identified by its number.

Traditional SIM cards have been through a few iterations throughout the lifecycle of the technology. It's perhaps hard to imagine now, but the first SIM resembled a credit card in size and weight! This is the first form factor of SIM, or 1FF, as referred to in the industry.

Following forms of SIM have been the mini-SIM (second form factor, or 2FF), micro-SIM (3FF), and most recently, the nano-SIM (4FF).

There is now also another form factor, the MFF2, which are embedded SIMs soldered onto the device circuit board. This is the preferred form factor for connected devices that move a lot of work in very harsh conditions.

Confusion arises when people assume that an embedded SIM (MFF2) has remote provisioning capabilities (eUICC) because MFF2 and eUICC are called eSIM. So which one is eSIM? 

To avoid any confusion, we suggest the following way of looking at the definition: "eSIM is the whole service - SIM + eUICC + platform; eUICC is the software that allows provisioning."

eSIM is a technology that can be present regardless of form factor. Take the relatively new iPhone XR, for example; it accommodates a removable SIM and has an eSIM service built-in, allowing users to purchase a plan from another carrier and use it alongside their contracted calls, messaging, and data plan.

To sum it up, eUICC is the software that allows a SIM to provision mobile network operators remotely, while eSIM is the whole service ecosystem. Neither is connected to the MFF2 form factor.

eUICC vs UICC

It might be helpful to draw a comparison between old and new when looking at eUICC.

The Universal Integrated Circuit Card (UICC) does a lot more than just the Subscriber Identity Module (SIM). It runs the SIM application while storing various information pieces such as the user's contacts list, enabling mobile data, and managing data roaming across multiple carriers.

So, what is the difference between UICC and eUICC? 

eUICC stands for Embedded Universal Integrated Circuit Card. However, eUICC is a SIM component that can be present in any SIM form factor to enable the eSIM service, including embedded. This is why many businesses confuse the embedded SIM MFF2 with an eUICC. 

The most notable benefit of having an eUICC-enabled SIM card is the ability to run over-the-air (OTA) provisioning of multiple network operator profiles from a central management point. Once provisioned, the SIM profiles on the card can be remotely managed and deleted if necessary.

OTA provisioning and management offers a level of flexibility that was not possible before eUICC was invented. User devices with an eSIM service can also be migrated in their hundreds in a matter of moments. We are still only in the early stages of the technology's lifecycle.