iSIM explained: what it is and how it differs from eSIM
July 28, 2023So, have you heard about the iSIM card? It's creating quite a buzz in the market, and today we're going to break it down for you.
First, let's talk about SIM cards in general. A SIM card, short for Subscriber Identity Module or Subscriber Identification Module, is a tiny plastic card that stores information about your mobile network connection. It holds important data like your International Mobile Subscriber Identity (IMSI), Integrated Circuit Card Identifier (ICCID), security authentication, ciphering information, temporary network-related data, and the list of services you can access. It even has two passwords: a PIN (personal identification number) and a PUK (personal unblocking key). With all this data, your mobile device can connect to the network, make calls, send texts, and access the internet. Some SIM cards can even store a limited number of contacts.
Now, let's look at the different types of SIM cards out there. First, note that we are your go-to team for customised software, iOS and Android applications. The first SIM cards were as big as credit cards, but over time, their sizes got smaller. We now have various sizes like the full-size SIM card, mini-SIM, micro-SIM, and the nano-SIM, which is the smallest and most commonly used in smartphones today.
But there's also a newer player in town: the eSIM. An eSIM, or embedded SIM, is a programmable chip that's embedded in your smartphone. It does everything a physical SIM card does but without the need for a physical card. It's carrier-independent and can be programmed to work on different networks. With an eSIM-compatible device, activating a new connection or switching carriers is as simple as downloading and installing a configuration file. You typically receive eSIM profiles as a QR code, which you scan and download to your device. Apple's iPhone 14 series, launched in 2022, was the first iPhone sold exclusively with eSIM in the US, and other phones have followed: the iPhone Air, released in September 2025, is eSIM-only worldwide; the iPhone 17 models and the iPhone 18 Pro and Pro Max, released in September 2026, are eSIM-only in 12 markets, including the US, Canada, Mexico, Japan, Saudi Arabia and the UAE; and Google's Pixel 10, Pixel 10 Pro and Pixel 10 Pro XL are eSIM-only in the US.
Now, let's move on to the star of the show: the iSIM. iSIM, or Integrated SIM, takes the eSIM technology to the next level. It integrates the SIM card directly into the system-on-a-chip (SoC) of the device. The SoC is the component that houses essential elements like the CPU, GPU, RAM, and mobile radio on a single chip. With iSIM, the SIM card becomes a part of the SoC itself, rather than a separate chip on the device's motherboard. Essentially, it allows devices to connect to a cellular network without needing a physical SIM card or a soldered eSIM on a printed circuit board (PCB).
The benefits of iSIM are remarkable. First, it saves a significant amount of space on the device since the SIM card is integrated directly into the SoC. For devices that exclusively use eSIM, this means there's no need for a SIM card slot at all. Additionally, as iSIM eliminates the requirement for a separate chip on the motherboard, it optimises internal space even further. This opens up more room for useful components and reduces the overall size of the device. Smaller sizes are particularly advantageous for devices like smartwatches, smart glasses, and standalone VR and AR headsets.
Another advantage of iSIM is enhanced security. Since the SIM card is integrated into the SoC, it cannot be removed or easily tampered with like a physical SIM card. Furthermore, iSIM often includes a Secure Processing Unit, making it even more secure and resistant to tampering.
Power consumption is another area where iSIM shines. It draws power directly from the SoC, unlike eSIM or physical SIM cards, which require a separate microprocessor to function. This low power usage is particularly beneficial for devices that prioritise energy efficiency, such as smartwatches and AIoT (Artificial Intelligence of Things) devices.
Speaking of AIoT devices, iSIM's small size and compatibility with existing standards make it an excellent fit for these standalone devices. It can help boost the popularity of AIoT devices and enable their seamless connectivity. If you are building such products, see our best practices for developing IoT products.
The main difference between eSIM and iSIM is that eSIM is a separate chip on the motherboard, while iSIM is integrated directly into the SoC of the device.
As for which devices support iSIM: in February 2023, Qualcomm and Thales announced the first GSMA-certified, commercially deployable iSIM on Qualcomm's Snapdragon 8 Gen 2 mobile platform, taking up less than one square millimetre of the chip. A capable chip is only the first step, though: the device maker and mobile operators also have to enable and support iSIM, so owning a phone with a Snapdragon 8 Gen 2 did not by itself mean you could use one. iSIM is already used in the Internet of Things, where low-power cellular chipsets such as Sony's Altair ALT1350 integrate the SIM for devices like trackers and smart meters. Forecasts vary widely: when they announced the certification, Thales and Qualcomm cited a forecast of 300 million iSIM shipments by 2027, while Juniper Research forecast in May 2024 that the number of iSIMs in connected devices would grow from 800,000 that year to more than 10 million by 2026.
So, that's the lowdown on iSIM, the most advanced type of SIM out there. It brings a host of benefits like space savings, enhanced security, low power consumption, and improved IoT applications. For now, eSIM is the technology to look for in a new phone, while iSIM is gaining ground in connected devices.
