Everything you need to know about IoT SIMs, Part I

Connecting the Internet of Things 

The Internet of Things (IoT) has been a concept since before the turn of the millennium, but it’s only been in the last few years that it was realized as a total paradigm shift, where connectivity became not just about people talking but also networking a vast array of physical objects – sensors, vehicles, appliances, industrial machinery, and more – to the internet.  

What is Internet of Things or IoT? 

The Internet of Things (IoT) refers to the network of physical devices, vehicles, appliances and other objects that are embedded with sensors, software, and connectivity, enabling them to collect, exchange and act on data over the internet. These smart devices can communicate with each other and systems to automate tasks, monitor environments or provide real-time insight. 

At the heart of the technology is a singular specialized component enabling cellular connectivity: the IoT SIM card. In terms of IoT applications, this is often referred to as a Machine-to-Machine (M2M) SIM.  

It’s different from the familiar SIM cards found in every consumer mobile phone for the last 20 years. IoT SIMs are engineered to provide more secure network authentication and ruggedly reliable connectivity to meet the unique demands of IoT applications, which can involve fleets of millions of devices operating globally. Their fundamental role is to act as a secure gateway, allowing devices to communicate data over cellular networks.     

This guide provides an accessible overview of IoT SIM technology, applications, core definitions, physical form factors, key technological features including durability, management, roaming, security, and power-saving capabilities, as well as the benefits and challenges associated with their deployment.  

Specialization in IoT SIMs 

While both standard consumer SIMs and IoT SIMs utilize Subscriber Identity Module tech to identify devices to a cellular network, their target applications diverge significantly.  

Standard SIMs are primarily optimized for connecting personal mobile devices like smartphones and tablets, facilitating human interaction with relatively high bandwidth requirements such as audio and video.  

In contrast, IoT SIMs are purpose-built for the diverse world of connected devices, ranging from remote environmental sensors and agricultural monitors to connected vehicles and industrial control systems.  

These applications involve machine-to-machine (M2M) communication, characterized by low data volumes, demanding high reliability, robust security, energy efficiency and near-constant connectivity.    

This fundamental difference in purpose drives several key distinctions: 

• Toughness 
  IoT devices are frequently deployed in the harshest environments, both natural and industrial, exposing them to extremes of temperature, vibration, pressure, humidity, and corrosion that would instantly destroy your average smartphone. IoT SIMs, particularly industrial and automotive grades, are constructed to withstand these harsh conditions.    

• Lifespan 
  IoT deployments often have operational lifecycles spanning many years, and accessing devices to replace components can be difficult or prohibitively expensive, especially in remote locations. Consequently, IoT SIMs are designed for longevity, often aiming for lifespans of 10 years or more, significantly exceeding even the most ambitious consumer devices’ lifespan.  

• Autonomy 
  Managing a fleet of millions of IoT devices requires remote administration. IoT SIMs are designed for bulk activation and ongoing management through specialized Connectivity Management Platforms (CMPs), allowing admins to monitor status, control connectivity, and manage data plans without physical access to the device. This contrasts sharply with consumer SIMs, which are typically activated and managed individually by the customer.    

• Flexibility 
  Maintaining a stable connection is paramount for many IoT applications. IoT SIMs often incorporate features like multi-network roaming and fail-over redundancy, allowing them to connect to various available networks within a country or region, thereby enhancing coverage, reliability and resilience against outages.    

• Efficiency 
  IoT data usage patterns differ significantly from consumer mobile usage. They’ll typically involve small but frequent packages of data being sent. IoT connectivity providers will offer plans tailored to this with features such as pooled data across the fleet and pay-by-use models, which are more cost-effective for low-bandwidth applications compared to typical consumer bundles.    

• Security 
  Each individual connection to a network represents a point of vulnerability. When a network features millions of devices that potentially connect hundreds of times a minute, the overall ‘attack surface’ becomes huge. This is why security is a major consideration. IoT SIM solutions often include enhanced security features not typically seen on consumer platforms, such as the use of private Access Point Names (APNs) to create secure network segments, the assignment of fixed IP addresses for reliable device identification and access control, and compatibility with Virtual Private Networks (VPNs) for encrypted data transmission.    

The above list only scratches the surface in examining the ways in which IOT SIMs are specialized, but is illustrative of how their features fundamentally reflect their operational contexts.  

Consumer devices prioritize human features, such as high data throughput, low latency and relatively short lifecycles in predictable environments at the cost of massive power consumption.  

IoT deployments, on the other hand, prioritize machine communication characterized by low data volumes but extreme reliability, longevity, robust security, and scalability across potentially vast numbers of devices operating in diverse and often harsh conditions – where maintenance and recharge might be years away.  

Total Cost of Ownership 

This difference is naturally reflected in the cost. Specialized industrial-grade IoT SIMs entail higher upfront cost compared to mass-produced consumer SIMs, but the total cost of ownership (TCO) over the extended lifecycle of an IoT device is optimized through features like data pooling, pay-per-use options, and the avoidance of costly manual interventions for SIM management or replacement.  

The economic evaluation shifts from the cost per individual SIM to the overall cost-effectiveness and operational efficiency of the entire IoT project.    

The Right Fit: Form Factors 

Selecting the appropriate physical format, or form factor, for an IoT SIM is a critical design decision.  

The choice depends on the physical constraints of the IoT device, the manufacturing process, and the environmental conditions that the device will experience during its operational life.  

Over time, SIM form factors have evolved. The original full credit-card sized chips (called 1FF or First Form Factor) are by now the subject of marvel and ridicule by younger generations, having since miniaturized and specialized into one of several general categories:  

To provide flexibility, especially for low-cost projects or retrofitting existing devices with standard SIM slots,  1GLOBAL offers a "3-in-1" SIM card containing pre-cut outlines allowing the user to punch out the required format.    

Ruggedized & industrial SIMs 

Ruggedized SIMs are adapted for harsher operating environments, although not necessarily with a whole new form factor. At first glance, some ruggedized and industrial SIMs are identical to the formats mentioned above, but built with tougher materials and construction techniques.  

Ruggedized SIMs will be built to operate reliably across wide temperature ranges, such as -40°C to +105°C, compared to the typical -25°C to +85°C range for standard or 'classic' grade SIMs. Their computational components will also be upgraded, with significantly higher read/write cycle endurance.  

1GLOBAL offers a minimum of 500,000 cycles for our removable SIMs, and up to 16 million cycles for MFF2 eSIMs. Data-retention is particularly susceptible to temperature fluctuation capabilities, which is why our  automotive-grade MFF2 will operate for 15 years even at 85°C.  

The ‘automotive grade’ is worth noting, in relation to a general 'Industrial' or 'IoT' rating. These are not necessarily distinctions in build quality,but reflect the far more stringent industry standards and safety certifications related to vehicle components, such as AECQ100 and PPAP (Production Part Approval Process).   

The eSIM Revolution 

In terms of the telco space as a whole, as well as the IoT industry, it’s hard to overstate the impact that embedded SIM (eSIM) tech has had. This small chip is typically around 6mm x 5mm and is soldered directly on to the device's main circuit board during manufacturing, rather than being inserted into a slot.    

While the physical embedding (MFF2) offers inherent manufacturing and structural benefits, the truly transformative aspect of eSIM technology happens in concert with the Embedded Universal Integrated Circuit Card (eUICC).  

What the eUICC does is enable Remote SIM Provisioning (RSP). Using a protocol officially standardized and codified by the GSMA, it allows the configuration data for specific carrier networks to be securely downloaded, activated, managed, and switched over-the-air (OTA) without needing physical access.  

The combination of eSIM, eUICC and Remote SIM Provisioning delivers game-changing advantages for IoT: 

(Even more) Durability, security and miniaturization  
Being soldered directly to the board makes the MFF2 eSIM highly resistant to physical shock, vibration, moisture ingress, and corrosion. It also prevents physical tampering or theft of the SIM card.  The small footprint of the MFF2 chip frees up valuable ‘real estate’ within the device, enabling smaller and more compact product design or expanded functionality.    

Logistical simplification  
RSP eliminates the need to manage inventories of different physical SIM cards for various regions or operators. Manufacturers can produce a single Stock Keeping Unit (SKU) version of their device with an embedded eSIM. The appropriate connectivity profile can then be downloaded remotely when the device is activated in its destination country or based on the specific service requirements. This dramatically simplifies global supply chains and manufacturing processes.    

Flexible & futureproof 
The eUICC allows multiple operator profiles to be stored on a single eSIM. Devices can be switched between networks remotely, avoiding vendor lock-in and allowing connectivity plans to be updated over the device's long lifespan, which is particularly valuable for devices deployed in inaccessible locations.    

Bootstrap connectivity 
To facilitate the initial profile download, eSIMs can be shipped with a pre-loaded 'bootstrap' profile. This profile provides basic, often limited, connectivity upon the device's first power-up, enabling it to reach the RSP platform and download its designated operational profile.    

eSIM evolved 

The most recent step in SIM evolution is the Integrated SIM (iSIM).  

Instead of being a separate chip soldered on to the board like an eSIM, iSIM functionality is integrated directly into the device's main processor, the System-on-a-Chip (SoC).  

The SIM operating system and credentials run within a dedicated, hardware-isolated secure area on the SoC, often referred to as a Tamper Resistant Element (TRE) or secure enclave. Functionally, iSIM relies on the same eUICC software architecture and RSP standards developed for eSIM, allowing for remote profile management.    

iSIM offers further potential benefits, particularly for resource-constrained IoT devices: 

(Even more) Miniaturization 
By eliminating the need for a separate SIM component entirely, iSIM achieves the smallest possible footprint (less than 1mm²), freeing up significant board space for other components, or enabling even smaller device designs.    

Reduced cost & complexity 
Integrating SIM functionality into the SoC reduces the Bill of Materials (BoM) by removing the cost of the separate eSIM chip or plastic SIM and tray. It also simplifies the device assembly process and supply chain logistics.    

Power efficiency 
Integrating the SIM function on to the main SoC allows for more holistic power management and optimization compared to designs using separate chips. This is particularly advantageous for battery-powered IoT devices, especially those using low-power network technologies like NB-IoT.    

The iSIM concept is standardized by industry bodies like the GSMA (under the term integrated eUICC or ieUICC) and is compliant with existing ETSI and 3GPP specifications.  

However, being a newer technology, its implementation requires closer collaboration during the manufacturing process, often involving a two-step personalization process shared between the SoC manufacturer and the iSIM profile provider.  

IoT SIM features & advantages   

Beyond their toughened physical form factor, IoT SIMs incorporate a range of tech features designed to meet the specific demands of the IoT industry and market. 

Global Connectivity 

Ensuring reliable connectivity, often across geographical boundaries, is critical for many IoT applications. IoT SIM solutions employ various strategies to achieve this: 

• Roaming Capabilities 
  IoT SIMs enable devices to connect to cellular networks outside their primary or ‘home’ operator's coverage area, which is essential for mobile assets like vehicles, trackers or products deployed internationally. As a specialist provider, 1GLOBAL offers extensive global roaming coverage, partnering with hundreds of carriers across 190+ countries.    

• Steered Roaming vs. Non-Steered 
  When a SIM is pre-programmed to preferentially connect to specific partner network chosen by the home operator, this is called ‘steered roaming’. This can lead to connectivity issues if the preferred network is weak or unavailable.  

  Alternatively, non-steered roaming allows the SIM to connect to any available network with the strongest signal, prioritizing connection stability (potentially at the expense of security and cost-efficiency). 

  An agile and ideal hybrid approach is to use steering rules, such as those deployed by 1GLOBAL, that selects partner networks based on both quality and cost metrics. 

• Multi-Network Access & Fail-Over 
  IoT SIMs produced by specialized connectivity partners will provide access to multiple cellular networks within a single country. This redundancy improves overall coverage and provides resilience if one network experiences an outage. This ensures minimal downtime.    

• Multi-IMSI  
  The most advanced SIMs include eUICC capabilities to store multiple International Mobile Subscriber Identities (IMSIs). Each IMSI represents a subscription profile for a different home network operator.  

  This allows the device to effectively switch its ‘home’ identity, which can be used to optimize costs, improve coverage by accessing different roaming agreements, or provide fail-over connectivity if the primary profile encounters issues. 1GLOBAL leverages its own patented multi-IMSI technology within its worldwide network architecture.    

• Network Technology Support 
  IoT SIMs support a range of cellular technologies, including legacy networks (2G, 3G where still available), modern high-speed networks (4G/LTE, 5G), and crucially, newer Low Power Wide Area Network (LPWAN) technologies like LTE-M (Long-Term Evolution for Machines) and NB-IoT (Narrowband IoT).

  LPWAN technologies are specifically designed for IoT use cases requiring low power consumption, extended battery life, deep indoor signal penetration, and cost-effective connectivity for transmitting small amounts of data.  

Hyper-scale management 

 When dealing with potentially vast fleets of connected devices, going unit-to-unit is no longer an option. Sophisticated, remote and highly automated management tools are essential. Two key components enable this: 

Connectivity Management Platforms (CMPs) 
These are software platforms, typically web-based portals with associated APIs, provided by IoT connectivity providers to allow businesses to manage their deployed SIMs. Using 1GLOBAL’s leading platform as an example, ideal CMP functionalities include:

• Lifecycle management 
  Activating new SIMs, suspending or reactivating connectivity, and permanently deactivating SIMs at the end of a device's life.  

• Real-time monitoring 
  Tracking data usage per SIM or across groups, monitoring connection status (online/offline), and potentially viewing device location information (often based on network cell tower triangulation).  

• Billing & rate plan information 
  Viewing assigned data plans, tracking costs, and accessing invoices.    

• Automation & alerts 
  Setting up rules based on usage thresholds (e.g., data limits), location changes, or other events, triggering notifications (email, SMS, API) or automated actions (e.g., suspending a SIM that exceeds its data cap).    

• Diagnostics & troubleshooting 
  Tools to check network registration status, send test SMS messages to devices, view connection history (Call Detail Records - CDRs), and analyze traffic patterns.    

• Reporting & analytics 
  Generating reports on inventory, usage, costs, rules triggered, etc., often exportable in formats like CSV.    

• Integration 
  Providing Application Programming Interfaces (APIs) – typically REST-based – to allow businesses to integrate CMP functions into their own enterprise systems or applications.    

• Administration 
  Managing user accounts, permissions, and potentially sub-organizations within the platform.  

Remote SIM Provisioning (RSP) 

The benefits of Remote SIM provisioning have been outlined in detail here, along with the capabilities to securely download and manage profiles over-the-air. These capabilities are central to the flexibility and logistical efficiency of modern IoT deployments, allowing connectivity to be configured and updated remotely throughout the device lifecycle.  

Sophisticated providers like 1GLOBAL offer M2M RSP platforms that support multiple hardware generations and network technologies, enabling remote management of profiles from various operators. Specific GSMA specs govern RSP for different device types (e.g., SGP.02 for traditional M2M, SGP.31/32 for newer IoT-focused RSP architecture).    

Stay tuned... 

Part II will delve deeper into IoT SIM security essentials, and also examine how solutions for lower power and long-life operability are delivering ever greater performance and control for remote fleet management. We will also look specifically at how 1GLOBAL’s IoT solution can help businesses hyperscale their ambitions in IoT.