eSIM vs. iSIM: How do physical SIM alternatives compare?

Smartphones are getting thinner and lighter every year, and manufacturers strive to remove as many redundant components as possible. The 3.5mm headphone jack was one of the first casualties of this effort about five years ago. Smartphone manufacturers are now moving away from SIM cards in favor of embedded SIMs or eSIMs and integrated SIMs (iSIMs). Both offer similar space savings, so why do smartphone manufacturers now prefer iSIM over eSIM? And will that change in the coming years? Here’s everything you need to know.

An embedded SIM (eSIM) is a digital version of a SIM card that is soldered to the mainboard of your device.

eSIM allows you to download carrier profiles over the air instead of inserting a physical plastic card into your device. Typically, your carrier will provide you with an authentication code or QR code to digitally activate your eSIM. You can download multiple such profiles to a single device and switch between them as needed. In this respect, eSIMs are much more convenient than physical SIM cards. This is especially useful for international travel, as you can download your eSIM profile before arriving at your destination.

Unlike iSIM, which we discuss in the next section, eSIM has already seen mainstream adoption across the mobile industry. Wearable devices such as Samsung’s Gear S2 and Apple Watch were among the first to adopt his eSIM in 2016. It’s easy to see why. Smartwatches are much denser than mobile phones and cannot contain a physical SIM card slot.

eSIM has become a staple feature of high-end smartphones within a few years of its introduction. Fast forward to today, and Apple has completely done away with the physical SIM card slot, at least in iPhone models sold in the US. eSIMs are popular not only in phones and smartwatches, but also in portable computing devices such as tablets and laptops.

Advantages and disadvantages of eSIM

The advantages of eSIM compared to physical SIM cards are:

• Convenience: Switch between multiple plans, carriers, and numbers with just a few taps.
• Space savings: eSIM-only smartphones can accommodate other hardware, such as a larger battery, instead of a physical SIM slot.
• More secure: Using a physical card allows attackers to perform SIM swap attacks. This involves taking her SIM from a stolen cell phone to send and receive confidential messages. With an eSIM, you won’t be able to bypass your device’s lock screen to access or copy your carrier profile.

There are also some disadvantages to eSIMs.

• Increased complexity: With a physical SIM, you just need to insert a piece of plastic. Transferring an eSIM between devices is not that easy and usually requires contacting your carrier by phone.
• Limited compatibility: Few devices still support eSIM, and many mid-range Android smartphones don’t benefit from it.

Integrated SIM (iSIM) takes miniaturization one step further by embedding the SIM into a device’s system-on-chip (SoC). His SoC in the smartphone already consists of several blocks in addition to the CPU and GPU, so adding a SIM as well seems like a natural progression.

iSIM represents a cleaner design compared to eSIM as it does not require a separate module on the device’s motherboard. This naturally leads to space savings. However, a big advantage of iSIM also comes in the form of security. Although an attacker can tamper with her eSIM module, it is very difficult to manipulate a locked down SoC. iSIM directly benefits from existing security protocols such as Arm TrustZone and provides robust protection against attacks.

Overall, iSIM is the most compact and secure SIM solution ever devised. However, there are still no smartphones or mobile devices that use this technology. Chipmakers and smartphone makers are unlikely to have reached an agreement yet, and the same is likely to apply to carriers.

Advantages and disadvantages of iSIM

There are three advantages of iSIM technology compared to physical SIM cards:

• Save space: iSIM eliminates the need for a SIM reader or card slot in your device.
• Security: iSIM provides the most secure SIM implementation, preventing access and tampering by hackers.
• Convenience: iSIMs are programmable, so you can switch carriers and plans at will.

As for the cons:

• Lack of adoption: Devices with iSIMs cannot currently be purchased.
• Complexity: As with eSIMs, moving SIMs between devices can be difficult. You may need to contact your carrier.

eSIM and iSIM both do away with the physical plastic SIM card, but they take slightly different approaches to doing so. Think of eSIM as a middle-ground option between two extremes. This gives you the most benefits. That means the ability to activate your plan over the air and switch between different profiles within the software. It also frees up maximum space, allowing larger batteries and additional sensors to fit into smaller devices.

iSIM is a further evolution of the concept of miniaturization, but instead focuses on security. When combined with the latest His SoC, the iSIM becomes virtually impenetrable. For some smartphone manufacturers, like Apple, who value privacy and security, iSIM is the obvious way forward.

That said, eSIM adoption continues to improve as more phones add support each year. On the other hand, we have not yet heard any rumors of a chip incorporating iSIM functionality.

As mentioned earlier, eSIM has become a fairly common feature in high-end and even mid-range smartphones. Additionally, some wearable devices and tablets are also equipped with this technology. Below is a list of phones and devices that support eSIM.

• Google: All Pixel phones back to Pixel 2, all Pixel Watch models
• apple: All mainline iPhones starting with XS, cellular Apple Watch models starting with iPhone SE 2nd generation.
• samsung: Galaxy S series from S20 onwards, all models of Galaxy Z Flip and Fold, Galaxy Watch Cellular Edition
• motorola: All Razr models, Edge 2022

Some smartphones from Nokia, Xioami, OPPO, and Sony also support this technology, so you should check if your smartphone is compatible with eSIM.

As for mobile phones that support iSIM, the list is empty for now. Chipmakers have not yet embraced this technology. The good news is that most of the work that went into supporting his eSIM on the software and carrier side can be reused for iSIM as well. We don’t know when it will finally start.