HomeCarriersThe difference between eSIMs and iSIMs, and the benefits for the IoT market

The difference between eSIMs and iSIMs, and the benefits for the IoT market

The SIM card, or subscriber identity module, is hardly perceived as cutting-edge technology, observes Vincent Korstanje, vice president and general manager of secure identity at chip-design company Arm. He conjures an image of “paperclips, staples, and stud earrings” as users attempt to eject their SIM cards, in increasing frustration.

Of course, Korstanje wouldn’t say so unless there is a sudden wave of innovation around the humble SIM. Which there is, and Arm is closely involved. But let’s start with the embedded (or electronic) SIM (eSIM), which already features in the latest smartphones and wearables from the likes of Apple and Samsung.

The eSIM will become the default connectivity hardware for most digital applications, reckons the GSMA, and is especially suited to small-scale and tamper-proof IoT devices. Korstanje calls the eSIM an “elegant, robust, and almost infinitely scalable solution” to the legacy SIM challenges in IoT applications.

How so? Because the eSIM does away with the swappable plastic SIM ‘card’, replacing it with a smaller SIM (about half the size of a Nano SIM), which is soldered permanently into the device. Authorised users can access and update profiles and other data on the eSIM via an over-the-air, remote SIM provisioning solution (RSP).

The GSMA has specified eSIM as a global solution, allowing users to store multiple operator profiles on a device simultaneously, and switch between them remotely – although only one can be used at a time. The operator association says its universal approach with eSIM will grow the internet of yhings by allowing manufacturers to build a new range of products for global deployment.

But Arm is taking this innovation further, by introducing integrated SIM (iSIM) technology, which moves SIM functionality into a device’s permanent hardware array. This “amplifies and extends” the advantages of the GSMA eSIM innovation, while also eliminating its shortcomings, says Korstanje.

“The iSIM no longer relies on a separate processor; nor does it demand a significant share of a device’s hardware footprint. Instead, iSIM enables hardware OEMs and processor design companies to design system-on-a-chip architectures that integrate SIM functionality with an existing, onboard processor and cellular modem,” he explains.

Arm suggests iSIMs will enable the same scale, security, and provisioning advantages of eSIM technology. It will also bring simpler design, and therefore lower costs.

Arm has appointed Vodafone as its global ‘bootstrap’ provider for NB-IoT and LTE-M devices based on its new line of iSIM designs. The Arm-Vodafone tie-up means all IoT chips based on Arm designs will default to the Vodafone network when they are switched on, and fall back to the Vodafone network in case of connectivity outages.

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