Before we try to answer the question posed in the title to this post, let’s step back and first try to understand the meanings of SIM, eUICC, and some of the other acronyms associated with mobile connectivity.
A subscriber identity module (SIM) is the chip card typically issued by a mobile operator that contains a mobile subscription. SIM cards are a universal integrated circuit card (UICC), which is the standard describing their physical and electrical characteristics. This subscription is technically called an international mobile subscriber identity (IMSI). The traditional SIM card issued by a mobile operator contains a single IMSI for the issuing operator. The IMSI is then used to authorize access to mobile networks, whether the home network or another network the device has roamed.
SIMs have come in a variety of physical formats; they started out back in the 1990s the size of credit cards, and gradually smaller and smaller form factors have been standardized as the devices became increasingly intricate. There is even an embedded SIM form factor, which is a tiny computer chip that can be soldered directly onto a circuit board.
All these types of SIMs are the same in terms of functionality. They provide a secure repository for the IMSI, ensuring authorized mobile networks can be accessed and keeping the IMSI safe to prevent it from being misused or replicated by a third party.
The eUICC (Embedded Universal Integrated Circuit Card) is different in that it provides a virtual filing system to store multiple virtual SIMs. These can also be remotely updated.
With the eUICC, to change the SIM, you only need to do a configuration change or over-the-air update, whereas with a UICC SIM, you must swap out the physical SIM card from the device.
Why the obvious choice for IoT connectivity may be eUICC
Although the eUICC is designed to allow multiple SIMs to be stored on the same device and for them to be remotely updated, each of the different profiles must be used separately. When changing the SIM profile used on an eUICC enabled device, you must go through a significant authorization process with a central authority.
Once the SIM swap is agreed to, the device will connect via a new “home” network, and a new IP address and phone number will be allocated to the device. Also, the device will have to update the APN (Access Point Name); this is a valid name for the gateway establishing the connection between the mobile network and the Internet or the enterprise’s network. If any of these steps fail, the device will be left unconnected. All of this creates complexity and requires time to complete.
Consider an Internet of Things (IoT) device. The manufacturer distributes devices globally and wants to avoid creating multiple SKUs (stock keeping units) for each place a device will be used. Loading a different SIM profile based on the product’s destination will create significant complexities and costs. Even within a single home country, the networks have different areas of coverage, which will be problematic for an IoT device tied to one network. For instance, a utility meter may be in a fixed location that’s covered only by one of the four networks in a given country. Remember if an eUICC-enabled device cannot connect from a location, it cannot be updated. So eUICC is not the right solution for every application.
It’s in situations like the above that multi-IMSI SIMs can provide a much simpler and more efficient solution. Multi-IMSI SIMs are regular physical SIMs, so they can operate with a much wider variety of existing equipment. Unlike regular SIMs though, multi-IMSI SIMs contain multiple IMSIs or mobile subscriptions. The device can switch between the subscriptions on the SIM, ensuring the best possible combination of price and coverage. The IMSI swaps can be made in real time as a device moves locations or a new network becomes available. Furthermore, when a switch is made between subscriptions, the device’s IP address and phone number and the APN configuration remain the same. This makes it possible to change the IMSI in real time, without requiring any reconfiguration of the IoT device’s connectivity.
With a multi-IMSI SIM, a manufacturer can install the same SIM in every device regardless of where in the world it will be used, maintaining a single SKU. Once the device is shipped and turned on, the multi-IMSI SIM will select the best IMSI for the networks available locally. If there is an IMSI better than those available on the SIM, it can be remotely provisioned onto the SIM.
It’s certainly worth taking a look at multi-IMSI SIM solutions when considering options for IoT connected via mobile.
Want to further engage with the IoT conversation? Join us at #SAPPHIRENOW on May 7-9 in Orlando for the “Transform Edge Computing with Intelligent IoT Connectivity” interactive session.