The world is evolving from nano-SIMs to eSIM and iSIM, but what does all this jargon me? The term SIM literally means Subscriber Identity Module, and it’s just a simple memory chip that holds identity information about cellphone users. SIM cards are usually integrated into a UICC (Universal Integrated Circuit Card), PVC cards with metal contacts.
SIM cards house many things including SMS memory (not used by modern smartphones) and personal contacts. The memory on standard SIM cards ranges from 8 KB to 256 KB, which is enough space for more than 250 contacts. However, nowadays it’s much safer to keep your contacts in the cloud than on your SIM card.
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The eSIM
This is an embedded SIM (eSIM) technology which is still a hardware-based SIM, but this elegant, robust, and scalable technology is soldered permanently into the device and was designed to address some of the challenges impeding true scalability in cellular IoT (see figure). eSIM allows devices to be deployed anywhere with existing cellular coverage. Operator profiles or network providers can be updated over the air, based on standards that offer a frictionless experience for device manufacturers and service operators.
iSIM starts with an eSIM
But there’s more: An integrated SIM (iSIM) takes all of the benefits of eSIM and embeds them into the device’s permanent hardware array by combining the SIM with the system-on-chip (SoC) architecture and cellular modem. Fusing the secure locations into the chipset itself offers a low footprint. It also introduces extra layers of security through a hardware-based secure enclave (a dedicated processor for security operations) that maintains the integrity of all cryptographic and key managed operations.
