SIMs, which were once made of plastic cards and later of motherboard chips, will soon be integrated into the SoC.
Qualcomm has announced at Mobile World Congress that the Snapdragon 8 Gen 2 is now certified as the “world’s first commercially deployable iSIM (Integrated SIM).” You may wonder what an iSIM is, especially after the recent transition to eSIM. However, iSIM is an improvement over eSIM, and it is the next step in the ongoing effort to shrink SIM cards. In brief, iSIM represents the latest advancement in reducing the size of SIM cards.
SIM cards, available in the smallest “nano” size, are tiny plastic cards measuring 12×9 mm that you insert into your phone to identify yourself to your cell carrier. SIM stands for “Subscriber Identity Module.” These cards enable your device to be provisioned for the cellular service that you pay a monthly bill for. The benefit of SIM cards is that you can easily transfer your service between phones by simply moving the SIM card, as long as there are no compatibility issues. This makes it convenient for you to switch to a new phone or use multiple phones.
Back in the olden days, SIM cards were used to store important data like contacts and messages. However, as smartphones became popular, this data was migrated to the cloud. Nowadays, SIM cards can only store up to 265KB of data on a 12×9 mm card, which is an extremely poor data density compared to MicroSD cards of a similar size that can hold up to 1TB of data, or about 4.2 million times more. Considering the mobile industry’s relentless pursuit of space-saving solutions, SIM cards take up a significant amount of space and are no longer necessary. As a result, they must be phased out.
Introducing eSIMs, the new standard in SIM card technology that eliminates the need for physical, removable cards by integrating a tiny chip onto your phone’s motherboard. The Google Pixel line adopted this technology in 2017, followed by the iPhone in 2018 and some Samsung phones in 2021, coexisting with physical cards in some models. Apple’s decision to phase out physical SIM cards in 2022 with certain iPhone 14 models marked a significant turning point for most carriers, resulting in eSIM-only devices that eliminate the need for card slots and simplify device design, saving space and reducing the risk of water damage. Instead of inserting a plastic card into the phone, users can provision their device through an app or by signing in to their carrier account. Compared to physical cards, eSIMs offer significant size savings, with the smallest chips measuring around 2.5 x 2.3 mm.
To fully optimize space in a phone, eSIMs, which are essentially chips that take up space on a motherboard, may not be ideal. Instead, the next step towards miniaturization is iSIMs, or Integrated Subscriber Identity Modules, which are integrated directly onto the System on a Chip (SoC). SoC integration is the technology that enables smartphones to be compact, as it consolidates various functions like the CPU, GPU, RAM, modem, and others into a single piece of silicon that does everything. This is a significant improvement over having individual chips, which require more space and power due to the need to create motherboard traces to connect them and the complexity of dealing with multiple chip packages.
The most cost-effective and space- and power-efficient approach to building electronic devices involves integrating all components into a single chip, using the smallest transistors available. This trend has led to the development of iSIMs, which will be integrated into the System on Chip (SoC) and measured in fractions of a millimeter. As chip manufacturing technology advances and process nodes shrink, iSIMs will become even smaller. This development marks a significant milestone in the evolution of SIM technology, as it will enable space-constrained devices such as smartwatches to benefit from this technology alongside smartphones.
Naturally, the cooperation of carriers is necessary, and Qualcomm’s recent announcement largely concerns this matter. The Snapdragon 8 Gen 2 SoC now being shipped includes the iSIM solution, which has been certified by the GSMA, the global association of mobile carriers. According to Qualcomm, the iSIM is fully compliant with the GSMA Remote SIM Provisioning standard, meaning that its subscriptions can be managed remotely through any standard platforms. This standard is the same as that used for eSIM, and it meets the same security requirements. Therefore, carriers that work with eSIM should not notice any difference between an eSIM and an iSIM. Ultimately, the iSIM is just a piece of silicon that requires software provisioning, so the location of the silicon should not matter to the carrier.
Although the iSIM is integrated into Qualcomm SoC components, its usage remains optional. In the case of current Snapdragon 8 Gen 2 phones, discrete eSIM chips are used instead of iSIM. However, now that the iSIM solution has been certified, the anticipation is for a phone manufacturer to incorporate it into their upcoming product design.