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An Essential Guide to IoT SIMs & Multi-Network Connectivity

A guide to IoT Connectivity, IoT SIM Cards & Multi-network Platforms
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What is IoT?

IoT is an acronym widely used for describing the Internet of Things. Typically, IoT is used on a vast range of devices viewed as inanimate objects designed to serve a particular function or use.

IoT devices, by their nature, tend to be geographically dispersed and installed at scale. Therefore, to perform effectively, they require some level of device intelligence, resilience, secure and legitimate connectivity, and the capability to be remotely managed.

IoT devices need to connect to the internet. They mostly do this by connecting through mobile networks via IoT SIMs, otherwise also known as M2M SIMs, Multi-Network SIMs or Roaming SIMs. 

Currently, there are over 35 billion IoT devices worldwide, which is, with that number is estimated to reach more than 75 billion by 2025. The use of IoT is spread across many sectors but is most prominent in:

What is Cellular IoT Connectivity?

IoT devices can offer a range of valuable public and commercial services for businesses and users, helping reduce costs and increase efficiency. However, these ‘smart’ devices require secure and resilient connectivity to operate beneficially and profitably.

IoT Connectivity can take a range of forms, but due to the benefits of portability, flexibility, and universality, IoT devices predominately use wireless systems. This most typically involves the use of the mobile GSM infrastructure.

What is an IoT SIM?

An IoT SIM, also known as an M2M SIM card, is a SIM card designed to be installed in a range of IoT Devices.

These cards provide both secure data storage and secure access to cellular networks, allowing IoT devices to connect to the internet without needing a Wi-Fi or other wireless network.

IoT SIMs are considered one of the common connectivity technologies used in IoT connectivity design and IoT connectivity management as they provide good IoT connectivity options for most types of IoT devices and use cases.

IoT SIMs also fulfil the need for scalability in IoT and massive IoT applications.

IoT SIMs come in a range of form factors so that they can fit in different types of IoT devices.

They can be fitted within a SIM slot or container and are therefore physically changeable or be fitted at manufacture as an embedded SIM or eSIM.

eSIMs need to be fitted with a high-quality global roaming IoT SIM or bootstrap profile, or a high-quality and supportable eUICC solution to ensure roaming flexibility and future-proofing of connectivity.

As IoT devices are usually stand-alone or mobile, they need to be managed remotely. IoT SIMs are therefore managed by IoT SIM Management systems, which provision them, set up their communications plans, activate, deactivate and record usage and generate billing.

The IoT SIM supplies the secure authentication for the IoT device to connect correctly to mobile networks, ensuring the signalling and traffic are routed securely and reliably via the correct system checkpoints and network nodes. 

These IoT SIM identifiers are also used for extra network features, such as Virtual Private Networks (VPN), and for setting and blocking certain features. SIM provisioning codes ensure billing is correctly apportioned to each radio and routing network, the originating user devices and the various service providers.

Typical Use Cases for IoT SIMs Include:

How do IoT SIMs Differ from Ordinary Consumer SIMs? (Specifics of IoT Connectivity)

IoT SIMs differ from those used in consumer mobile devices in a number of important ways.

IoT SIMs are designed specifically for use in Internet of Things devices, often needing less power and having a wide network range despite having a lower data rate and more security options. This helps ensure the IoT device has a reliable connection to the internet at all times, allowing it to deliver accurate data when needed.

In addition, many IoT SIM come with special features such as Multi-Network roaming, allowing IoT devices to search for the best connection available and switch between networks on the fly.

IoT SIMs are securely coded at their manufacture and then provisioned by the IoT Mobile Virtual Network Operator (MVNO) for an assorted range of approved IoT applications.

Through commercial agreements between mobile network operators (MNOs), IoT Virtual Mobile Network Operators and infrastructure providers, IoT SIMs can maintain a reliable and extensive connection to networks.

IoT SIM Formats

There’s no one-size-fits-all solution when it comes to IoT SIMs. They are manufactured in a range of form factors and chipsets to suit a variety of IoT devices.

This can include various sizes and embedded chips designed for more miniature or environmentally challenging environments such as high levels of motion or vibration. 

All IoT SIM formats (including chip SIM cards) provide secure IoT SIM credentials that enable device verification, access and encryption on a local mobile available network, broader internet data networks and global network infrastructure.

For more severe applications, industrial SIM card technology provides greater protection for extreme temperatures, environments and vibration.

Elements of IoT Connectivity and IoT Connection Types (Overview of IoT Connectivity)

IoT SIMs and their Roaming Agreements [Wide Area Network(s)] 

For their continued long-term connection, it is therefore crucial that they are identified as authorised IoT devices and remain protected by legitimate commercial IoT device agreements with those host mobile network operators who are vital for providing the radio and base station switching networks.

Most MNOs welcome authorised IoT agreements with credible and trustworthy IoT MVNOs as they provide reciprocal forms of revenue streams without the headache of excessive or unconstrained signalling which can significantly degrade general network performance.

IoT Roaming interfaces and agreements are typically provided by the IoT or roaming part of a MNO organisation.

They work with other MNO and MVNO mediators to provide seamless IoT connectivity.

Therefore, these IoT roaming network architectures must have resilient network topology, individual network components and security.

Remote Management of IoT SIMs for IoT Applications

Remote management is essential with any IoT devices, as they typically cannot be managed locally by their users/owners or retail outlets.

Because of this, IoT SIMs require configuration changes to be made remotely and securely, and their costs to be continuously monitored and controlled independently of the Mobile Network Operator’s systems.

IoT SIMs and their networks use remote monitoring systems to ensure maximum service up-time. 

IoT Connection Types and IoT Connectivity Comparison (Connectivity Essentials) 

There are various connection types that enable communication between IoT devices and cloud services.

Cellular networks like 2G, 4G and 5G play a significant role in IoT connectivity, particularly in scenarios where devices need to operate remotely or in areas without Wi-Fi coverage or require low power consumption .

These cellular networks provide a more extensive range and higher bandwidth, enabling continuous data transmission and remote control over connected devices.

Another common IoT connection type is Wi-Fi, which allows devices to connect to the internet wirelessly within a certain range. This enables easy integration and control of smart devices, such as smart home appliances or industrial machinery.

Wi-Fi, however, is power-hungry and usually needs a mains power supply.

Despite this, Wi-Fi can be a suitable connectivity technology as it can act as an edge wireless IoT network for those devices that need very local wireless technology coverage. However, extra Wi-Fi network security implementations would be needed.

Other technologies, such as very short-range radio devices, are also used in IoT. For example, another widely used connection type is Bluetooth, which facilitates short-range communication between devices.

Bluetooth is commonly used in wearable devices, such as fitness trackers or smartwatches, where a constant connection with a smartphone or other devices is required.

In addition to these IoT connectivity technologies, some IoT devices use short range smart home technologies such as ZigBee and Z-Wave for providing seamless connectivity and mesh protocols as part of their IoT offerings.

For devices that need a longer range, GSMA key technologies NB-IoT and LTE-M provide cellular IoT narrowband low-power consumption solutions.

LoRaWAN similarly offers narrowband IoT where low power consumption but needs proprietary IoT gateways to operate. 

By offering diverse connection types, different network technologies and a range of power consumption to suit different types of IoT devices and use cases, the IoT ecosystem ensures that devices can communicate seamlessly, opening up a world of opportunities for automation, efficiency, and connectivity in various industries and everyday life.

So, whether you are controlling your home’s lighting system or managing a fleet of vehicles, the selection of the right IoT connection type, power consumption and communication protocols is crucial for a successful and robust IoT network.

IoT Connectivity

Why Use a Multi-Network Connectivity Solution for IoT Devices?

Most IoT devices use multi-network connectivity systems which are authenticated by or powered by IoT SIMs. A multi-network system is a type of IoT solution that leverages multiple different networks to provide the best connection for an IoT device.

This can include both cellular IoT and satellite networks and related IoT technologies, allowing an IoT device to remain connected even if one of the networks fails. This ensures the device has a reliable connection and reduces the risk of data being lost. Multi-network connectivity allows IoT SIMs to connect to any radio network within a particular country.

Motivations for using multi-network connectivity and cellular technology include:

The Benefits of Multi-Network IoT SIMs

Multi-network systems provide substantial benefits for IoT service providers, given that they are carefully managed. Consumer mobile phones typically remain connected to one network due to the competitive nature of that use case.

By employing commercial IoT roaming agreements and investing in interfacing systems and technologies, however, IoT MVNOs can deliver multi-network capability for IoT devices. Allowing them to connect to the most favourable network based upon their local, physical, geographical, or temporal circumstances.

Using the existing GSM mobile network infrastructure in this way, therefore underpins most public and commercial IoT services. Providing the ubiquitous access needed and the ability to legitimately authenticate devices on the various mobile networks and their visitor location registers. It is important, however, to ensure optimum IoT roaming infrastructure to ensure minimal latency and high network security measures.

A managed IoT SIM with robust connectivity plans will, therefore, enable its associated IoT device to connect to multiple networks, supplying resilience, flexibility, and service performance.

As IoT devices are released and move or travel, the ability to connect to the widest variety of mobile networks in a region or across borders, ensures services are not interrupted, while avoiding unexpected out-of-zone penalties. In mobile environments, such multi-network capability helps increase overall capacity and improves data rates (, 2018).

It is also key that IoT SIMs are supported by a SIM Management Platform together with a flexible approach and the ability to change tariffs and suspend SIMs. IoT devices cycle through various lifecycles which to be cost-effective require that the connectivity and associated costs be switched off during these ’downtimes’. 

What Roles do IoT MVNOs and IoT SIM Providers Play in the Sector?

Selecting the right connectivity and IoT SIM partner is critical, not only in helping choose, configure, and optimise device’s connectivity with minimum latency via optimum IoT network design, and with the necessary long-term commercial IoT agreements, but also to provide real time advice and support should any of the MNO’s networks or devices suffer issues.  

Indeed, some compatibility issues may require more involved investigations. This is where a partner with high levels of telecom network expertise and resourced support structures is invaluable.

Close relationships with our customers and partners also ensure that providers such as Caburn Telecom constantly monitors and tests networks; often advising MNO problems to our clients in advance of the networks detecting problems themselves. 

Caburn Telecom’s large client network also helps us to continuously monitor service levels and user experiences. This is achieved by advising in good time of network features, upgrades, or sunsets.

Safeguarding technologies which match the desired evolution and lifespan of devices is important, as the costs of a retrofit of dispersed devices is viewed as a failure of foresight. 

The Importance of Legitimate IoT Roaming Agreements for IoT SIMs and their Connectivity Solutions

A high-quality IoT connectivity partner also ensures communication plans, connectivity technologies and agreements match use cases.

MNOs dislike their networks being infiltrated by undisclosed M2M / IoT device signalling and closely monitor these situations. This is a crucial part of IoT network requirements ensuring IoT devices can and are able to remain connected.

Spotting IoT SIM profiles not in line with their connectivity plans and pre-agreed commercial arrangements means they may unilaterally apply extra surcharges for those groups of devices, or permanently block those ranges of IoT SIMs. 

A high-quality cellular IoT provider, therefore, also invests in optimising and upgrading their networks and works closely with MNOs to create strong, mutually beneficial relationships.

Global IoT Connectivity

IoT SIMs & Single Network Coverage Claims

Coverage Data: Crowdsourced Data or MNO Provider’s Maps?

Each individual network’s extent of mobile radio coverage is contentious.

Coverage maps are usually provided by MNOs themselves or via crowdsourcing mechanisms. Coverage can be patchy, however, and newer network architecture technologies are usually deployed based upon likely returns on investment or economic factors.

This means that rural or poorer areas are usually less well served , as service voids remain and local availability of 2G, 3G, 4G and 5G operational infrastructures vary.

MNOs are also looking to farm radio spectrum or optimise power use. This can create changes or fluctuations. 

Indeed, coverage maps tend not to objectively reflect the operational experience of users (, 2018).

This is particularly important for national deployments which may require service ubiquity and high coverage.

Moreover, cities are not exempt. Buildings and indoor locations can attenuate networks which means an alternative mobile network is needed.

High general usage can also reduce the performance of an individual network, which means alternatives need to be available.

Crowdsourcing data conflates indoor and outdoor measurements and does not reflect device characteristics, handling or limitations (, 2015).

Confusing the significant effects that buildings and structures have on reducing signal strength. Similarly, the impact of attenuation, poor weather, radio shadows, operational voids, weak signals and temporal variations tend not to be considered.

Please find below some online resources for checking or benchmarking network coverage or expected network performance:

All Regions:

  • GSMA – Network Coverage Maps
  • IoT Deployment Maps: (, 2023) GSMA | Mobile IoT Deployment Map | Internet of Things 

EU: European Commission:

UK Coverage

USA Coverage:

Actual User Experiences: IoT Device and IoT SIM Performance

Device connectivity also depends upon a dynamic range of local and core-network system interactions, which affect performance and service levels.

For these reasons, and due to the nature and complexity of mobile networks, it is recommended that actual user experiences (client-assisted data) form part of the measurements.

These are continuously checked to factor in environmental, temporal, and contextual changes.

Multi Network IoT SIMs

These practical problems mean experienced IoT service providers typically extend geographical and temporal service levels via a multi-network approach.

In the consumer and business markets, the main mobile network operators are competing, making neutral cross-relationships unworkable. 

Multi-network providers like Caburn Telecom, however, work to deliver a structure that allows devices to select and communicate with the best network available. This is achieved by producing an IoT SIM that is accepted by each of the MNOs via long-term agreements.

By providing a single IoT SIM with a world-class global IoT roaming profile, Caburn Telecom are able to deliver to our customers a single SIM SKU which can be fitted in the factory.

This is complemented by our eSIM and eUICC services which offer a comprehensive choice of IMSI profiles. This ensures that IoT data packages suit the business and cost profiles needed by large-scale clients with the ability to connect over multiple carriers.

High Quality IoT SIMs and their Support Systems

A high-quality IoT multi-network provider ensures these roaming agreements reflect the type of devices and their expected connectivity profiles.

For example, while early M2M devices and their traffic tended to involve small data packets, increasingly devices require human interaction or supply some level of service experience for the user – be it voice quality, latency, speed of service, privacy, or security.

Increasingly, much broader use applications recognise the benefits of multi-network connectivity and look to integrate them into wider service offerings.

Mission Critical IoT Services

IoT SIM solutions for mission-critical services including vehicle telematics, insurance, lone workers, telehealth, telecare, assisted living, epos terminals, hot-spots, routers, personal security devices, CCTV, bodycams, asset security and management systems all rely on multi-network connectivity. 

In these sorts of user and device interactions, it is important to consider not only the quality of service but also the quality of experience as well as providing real-time monitoring and warning systems.

Internet of things, car connectivity

Mobile Systems and Device Interrelationships with IoT SIMs

Mobile systems are convoluted and when combined form complex ecosystems.

Ubiquitous access depends not only upon the specialised IoT SIM variant but also on the device’s compatibility with the various radio frequencies and the variety of network evolutions supported by each network. 

For example, approved modems, the access technologies available and each network provider(s) regional and national implementation and disposal of 2G, 3G, 4G and 5G infrastructure.

IoT SIMs and IoT Devices

A global IoT SIM and the multi-network characteristics of the IoT device are also affected by the capabilities of the IoT device itself.

Vast arrays of devices have different levels of network intelligence or selection logic. Some are battery-powered and others are connected to the mains supply. 

In IoT devices, the SIM card is available as an ‘on-demand IoT SIM’ for reading and polling by the modem hardware and firmware as required. This is typical through the use of AT commands to instruct the modem and its communications.

Remaining connected to the network, or the need to close connections in sleep and hibernation modes to conserve battery life will vary by circumstance.

Some will have simple network selection algorithms based on signal strength, while others will have more astute selection procedures. For example, the firmware can be designed to select networks manually or automatically.

More intelligent devices can use network evaluation steps/algorithms for selecting the best network to connect with.

Selecting the Strongest Signal or Network Selection Algorithms?

While the most primitive devices will select based on the strongest signal only, irrespective of bandwidth or services available, others can select based on the availability of the required services and unique communication requirements.

Alternatively, some devices will ping certain data services to first measure end-to-end data connectivity. 

For instance, selecting a network based simply on signal strength may mean that a 2G or 3G network is selected when a slightly lower strength 4G one is available.

This may not matter for those applications requiring a simple voice connection, but for those needing data only, it can severely affect service or performance.

This device capability is also important as devices may need to intelligently select or switch networks in certain circumstances, for example:

  1. If the local strongest measured signal by the device is 2G, but data connectivity is required; 
  2. One of the MNOs suffers core network issues, which to the device appears that a network is available when end-to-end connectivity on that network is not possible; and 
  3. Other contextual or temporal factors meaning the loss of a radio connection or time-outs, which the device will need to have processes in place to manage.

Network selection criteria becomes especially important when there is congestion on one of the networks or an outage.

This is crucial as a catastrophic failure on an individual MNO core network could result in hours of downtime on that network, while investigation, rectification and recovery works are implemented. This can sometimes involve load balancing and management of traffic congestion through points of failure or constriction.

The ability to select another network in this scenario is invaluable. Eliminating such periods, where none of the population of IoT devices can communicate for an extended period.

The Role of eUICC, eSIM and Multi IMSI in IoT SIM Selection

Embedded SIMs provide a useful solution for incorporating a small IoT SIM chip directly on a printed circuit board with no need for a seperate SIM slot.

For saving space and high-vibration use cases such as industrial and automotive, they can provide many benefits. The obvious drawback is that the IoT SIM cannot be swapped as there is no SIM carrier or slot.

eUICC technologies enable the mobile carrier to be changed or at least a selection to be loaded at manufacture or over the air.

While this technology is well suited to eSIM modules, it can also be applied to traditional plastic SIM cards at manufacture.

Multi-IMSI IoT SIMs offer numerous advantages. For example, having more than one roaming profile means that regional cost variances can be more flexibly accommodated by changing the roaming carrier depending upon the device location.

It also means that if there is an outage on one roaming carrier network, the IoT device can select another. This increases uptime and resilience.

Of course, IMSI profiles come at a cost, so having the best and most efficient selection of Tier 1 carriers is important.

However, having too many profiles may not meet the connectivity cost budget.

Keeping data secured using a virtual private network (VPN)

About Caburn Telecom; our IoT SIMs, Global Reach and Management Services

Caburn Telecom are a leading global provider of connectivity for Internet-of-Things (IoT) devices.

Our focus is the development of advanced mobile connectivity solutions and associated management systems.

Our IoT SIMs, chip-SIMs and eSIMs provide the flexibility and high service levels vital for distributed IoT devices to operate effectively. We provide multi-network capability together with the streamlined management of IoT SIM populations.

Caburn Telecom’s secure client portals deliver easy-to-use interfaces for understanding and administering the connectivity of devices. Traffic details and actual (and predicted) costs can be viewed at the group(s) and the individual level.

Our innovative and flexible connectivity packages allow IoT service providers to maximise their assets and manage the operational life cycles of devices.

We provide global IoT multi-network roaming SIMs, EU-wide plans, eSIM, eUICC SIM options, North American Solutions, Pan-African IoT SIMs, South and South East Asia, China, Middle East, Latin America, UK and Ireland high data IoT SIM cards solutions. 

Please contact us to discuss your IoT project and how our IoT solutions and IoT SIMs can power your cellular connectivity. Our IoT data plans are flexible and cost-effective.

We provide multinetwork IoT SIMs, IoT eSIM and eUICC IoT SIMs, enabling us to provide global coverage for your IoT projects and IoT deployments.

Becoming a client or partner of Caburn Telecom means that we will help you take control of your IoT network.