What is an eSIM and how is it used in IoT?

The SIM card has been around since the early 1990s. It is a small, removable piece of silicon and copper encased in plastic. Each manufactured SIM has a globally unique serial number called an ICCID (Integrated Circuit Card ID), along with an IMSI and IMEI, to identify it on the network. There are pads to interface to a modem or a processor, allowing the device to authenticate on a network as unique. If that unique SIM device has a plan with a carrier, the data from the modem or processor is allowed to pass through the network to some endpoint — either a server or telephony system.

Key takeaways

• An eSIM is a chip soldered directly to a device's circuit board, while eUICC is the software component that enables over-the-air profile updates without physical SIM replacement.
• eSIMs simplify global manufacturing by enabling single-SKU production and remote carrier provisioning after deployment, eliminating the need for costly field recalls when switching networks.
• Industries like healthcare, connected vehicles, industrial IoT, and micromobility benefit from eSIMs through sealed device designs, remote provisioning, and future-proofing against network sunsets.

What is an eSIM?

An eSIM (embedded SIM) is a small chip soldered directly to a circuit board inside a device, making it non-removable. The "e" stands for "embedded"—not "electronic"—and the official form factor is called MFF2. Like traditional SIMs, eSIMs use unique identifiers like the ICCID to authenticate devices on cellular networks.

The terminology has evolved since eUICC entered the IoT landscape. Today, most people use "eSIM" to mean an eUICC-capable SIM. Here's the distinction:

• eSIM: The hardware component—a chip soldered to the board
• eUICC: The software component that enables over-the-air (OTA) profile updates

Recommended reading: 5 benefits of building with eUICC

What are the differences between standard SIMs and eSIMs?

To understand the differences between standard SIMs and eSIMs, let's take a closer look at how each one works.

How do SIM cards work?

If you have an IoT device with a slot for a traditional SIM, here's how you connect:

1. Choose a provider and data plan.
2. Receive a SIM card programmed with your network credentials.
3. Insert the SIM into your device.
4. The device authenticates on the network using the SIM's unique identifiers.

Switching providers means physically removing and replacing the SIM card.

How do eSIMs work?

Choosing an eSIM requires upfront planning since it's soldered into each device during manufacturing. You'll need to coordinate your supply chain to ensure eSIMs are available at the assembly stage. Once devices are built with eUICC-enabled eSIMs, connecting to the network follows this process:

1. Use a built-in bootstrap profile to establish an initial network connection.
2. Download a profile (or multiple profiles) through an over-the-air (OTA) provisioning process.
3. Once the SIM profile is downloaded and installed, the network recognizes it, and the device uses it just as it would a physical SIM.

Recommended reading: How Multi-IMSI and cellular IoT work together

Benefits of using eSIMs

While it takes more advanced planning to incorporate an eSIM in your IoT device, the technology offers several key benefits for businesses. Let's take a look.

Pros of eSIMs

• Simplify global manufacturing: The embedded form factor eliminates manual SIM insertion and allows for more compact, sealed devices. Provision SIM profiles after deployment to create a single global SKU that ships anywhere.
• Avoid expensive recalls: With traditional SIMs, switching carriers means physically replacing cards in every device. With eSIM, push new profiles remotely via RSP—no field recalls required.
• Get flexible coverage: A single-carrier SIM limits you to one network's coverage footprint. eSIMs enable flexible network selection after deployment based on signal strength and location.

Recommended reading: How to get started with eUICC for your deployment

Cons of eSIMs

• Less simplicity in some cases: If devices are easily accessible and you expect frequent carrier changes, traditional SIMs may be more practical.
• Limited network support: While eSIM adoption is growing, OTA provisioning isn't universally supported. Verify local network compatibility before deploying globally.
• Permanent traceability: Because eSIMs can't be removed, devices remain trackable unless fully dismantled.

How can eSIM and eUICC impact my business?

eSIM technology reduces hardware complexity, simplifies global logistics, and future-proofs devices against network changes. The impact varies by industry. Here's how a few verticals benefit:

• Healthcare devices: Sealed, durable designs that withstand moisture, temperature, and vibration
• Connected vehicles: Remote provisioning after shipment to match local network requirements
• Industrial IoT: Single-SKU manufacturing with future-proofing against network sunsets
• Micromobility: OTA updates for e-bikes and scooters plus theft-resistant embedded design

Frequently asked questions

What future possibilities does eSIM technology enable?

eSIM technology is paving the way for innovations across IoT and consumer applications. As networks evolve and 5G expands globally, eSIMs will enable seamless multi-network switching, allowing devices to automatically select optimal carriers based on coverage, cost, or performance. Future possibilities include truly autonomous device provisioning at scale, dynamic network slicing for specialized use cases, and simplified global product launches without regional hardware variants.

As the technology matures, we'll likely see eSIMs supporting more sophisticated security protocols, enabling zero-touch onboarding for massive IoT deployments, and facilitating new business models around flexible, on-demand connectivity.

What are the advantages of an eSIM?

eSIMs enable streamlined global manufacturing with single-SKU production, eliminate the need for physical SIM card handling, and support remote carrier provisioning after deployment. The permanent installation creates more durable, sealed device designs ideal for harsh environments and reduces the risk of connectivity loss from loose or damaged SIM cards.

Do I need to put my SIM card in if I have an eSIM?

No, eSIMs are soldered directly to the circuit board and authenticate on cellular networks without any physical card insertion. Many devices support both eSIM and traditional SIM slots simultaneously for dual connectivity options.