SIM technology has come a long way—from physical cards to fully embedded software. As IoT deployments expand across industries and geographies, the need for more adaptable, secure, and remotely manageable connectivity has grown just as fast.
Today, solutions like Soft SIM, eSIM, and iSIM offer distinct approaches to provisioning and managing cellular access — each with its own advantages, limitations, and ideal applications.
In this post, we’ll break down the key differences between these SIM technologies and help you determine which is best suited for your IoT deployment.
Soft SIM explained
A Soft SIM is a software-based implementation of SIM functionality. Instead of using a physical card or embedded chip, it stores the SIM profile—including the IMSI and authentication keys—within the device’s memory or processor. Once provisioned over-the-air (OTA), the profile allows the device to connect to cellular networks in the same way a traditional SIM would, supporting standards like 3G, 4G, and 5G.
Unlike eSIM or iSIM, Soft SIMs lack a hardware secure element and are not governed by a standardized global framework, which impacts adoption and support across mobile operators.
Pros
- Saves space by removing the need for physical SIM components
- Reduces manufacturing and logistics costs
- OTA provisioning supports large-scale, scalable IoT deployments
Cons
- Relies entirely on software security—no hardware isolation
- Limited adoption and support from carriers due to security and compliance concerns
- Often requires tight coordination between OEMs and MNOs
- Proprietary implementations can lead to vendor lock-in
What is eSIM (eUICC)?
eSIM is commonly used to describe SIMs that support remote provisioning, but technically it refers to the form factor—an embedded SIM card (e.g., MFF2). The technology enabling remote profile management is eUICC (Embedded Universal Integrated Circuit Card), a GSMA standard that allows a single SIM to store and switch between multiple mobile network operator (MNO) profiles.
Unlike legacy SIMs, which hold only one profile, eUICC-enabled SIMs can be provisioned and updated over the air. eUICC is not limited to embedded SIMs—it can also be implemented in removable SIMs and integrated SIMs (iSIM).
The GSMA’s Remote SIM Provisioning (RSP) framework includes:
- SGP.22 (Consumer): End user-initiated downloads for devices like smartphones.
- SGP.02 (M2M): Operator-controlled provisioning for unattended or industrial devices.
- SGP.32 (IoT): Built for IoT, enabling asynchronous, low-power profile updates.
Pros (SGP.32)
- Supports OTA provisioning and remote profile management
- Enables bulk provisioning for large-scale IoT deployments
- Optimized for low-power, low-bandwidth devices using lightweight profiles
- Removes reliance on SMS, enabling non-IP protocols like NB-IoT and LPWAN
- Compatible with existing SM-DP+ infrastructure
- Supports localized profiles to meet compliance in global markets
Cons (SGP.32)
- Operator support varies, and market adoption is still maturing across regions
- Switching carriers requires commercial agreements and coordination
- Profile hosting and switching may involve recurring costs
- Backend integration (e.g., APNs, VPNs) can be complex for smaller teams
What is iSIM?
An iSIM (Integrated SIM) embeds SIM functionality directly into a device’s main processor (System-on-Chip), eliminating the need for a separate SIM card or embedded chip. This integration reduces space, lowers power consumption, and improves durability—making iSIM ideal for compact, power-sensitive IoT devices and wearables.
iSIM supports the same core functions as traditional SIMs, including network authentication. When combined with eUICC, it also enables remote provisioning and profile management.
Pros
- Eliminates separate SIM hardware—greatly reducing device size
- Ideal for compact, space-constrained IoT devices
- Lower power usage by utilizing processor resources
- Strong security via processor-based Trusted Execution Environments (TEE)
- Fully supports remote provisioning and profile management standards
Cons
- Requires specific SoC support—limited to certain chipsets
- Operator ecosystem support is still evolving
- Less practical for dual-SIM or multi-SIM setups
- Adoption is growing but not yet ubiquitous across all IoT use cases
Which SIM Is Right for Your IoT Deployment?
Choosing between Soft SIM, eSIM, and iSIM depends on your specific IoT use case—there’s no one-size-fits-all answer. Whether it’s form factor flexibility, security requirements, or provisioning needs, each SIM type serves different priorities.
At Velocity IoT, we deliver flexible, future-ready connectivity solutions built on eUICC and multi-IMSI technology. Whether your deployment calls for a plastic SIM, embedded eSIM, or integrated iSIM, our solution is form-factor agnostic—designed to work across all device types and use cases. With support for remote provisioning, dynamic network switching, and a single vendor relationship, Velocity IoT helps you achieve global, cost-efficient, and resilient IoT connectivity.
Let’s connect—discover how Velocity IoT can power your next deployment.
