What is Multi-IMSI and How Does it Work?

OEMs face potentially high costs and technical barriers when managing devices roaming across multiple international networks without the appropriate SIM solution. Multi-IMSI technology offers a path to global scalability for OEMs, making it easier to manage devices in a wide range of locations without being tied to a single network provider in each country.  

But is multi-IMSI the best solution for global connectivity? While multi-IMSI SIMs offer flexibility, they come with their own set of challenges. Alternatives, like e-SIMs and global roaming SIMs, may offer more scalable and future-proof solutions. 

The choice of SIM technology is more than a technical decision; it's a strategic one that influences the success and scalability of your IoT deployments worldwide. In this article, we will explore the nuances of multi-IMSI SIMs and their advantages, disadvantages, and alternatives to provide you with an informed viewpoint on selecting the most suitable global SIM for your devices.

What is a multi-IMSI SIM?

A multi-IMSI SIM allows a single SIM card to store and switch between multiple subscriber profiles. With a multi-IMSI SIM, devices can seamlessly roam across different parts of the world by dynamically selecting a local carrier profile for each region. This technology maintains continuous network access across various regions without needing physical SIM swaps or multiple SIM cards. 

What is an IMSI?

The IMSI, or International Mobile Subscriber Identity, is a 15-digit unique code stored on a SIM card that serves as the device’s identification within its SIM. With an IMSI, mobile networks authenticate and track a device. The numbers that make up an IMSI include: 

• A Mobile Country Code (MCC) that identifies the subscriber's country
• A Mobile Network Code (MNC) that specifies the subscriber's home mobile network
• A Mobile Subscriber Identification Number (MSIN) that uniquely distinguishes the individual subscriber within the network

What is a multi-IMSI?

Unlike standard SIM cards, which are bound to a single IMSI and a single network operator, multi-IMSI SIMs are equipped with several IMSIs from different carriers worldwide. This allows a device to switch between network profiles, optimizing connectivity based on location, network strength, and cost-effectiveness.

Including multiple IMSIs in a single SIM card eliminates the challenges and inefficiencies associated with manual SIM changes or the need for multiple SIM cards when a device crosses international borders. However, once the IMSIs are loaded onto the SIM, you can’t change them later. 

Multi-IMSI vs. e-SIM (eUICC)

The eUICC (Embedded Universal Integrated Circuit Card) SIM is a unique but similar alternative to the multi-IMSI SIM. e-SIM typically often refers to embedded hardware and the eUICC software. This innovative technology allows for the remote provisioning of carrier profiles, meaning profiles can be removed, managed, or added remotely without needing to physically access the SIM card. 

As a GSMA-standardized solution for provisioning, the eUICC SIM ensures compatibility and interoperability across global mobile networks. It also enhances security by enabling secure and seamless transitions between network operators, making it an ideal solution for devices requiring flexible and secure connectivity options.

Similarities

Multi-IMSI and eUICC SIM share several similarities, particularly in how they manage subscriber authentication and connectivity. Both technologies are designed to store multiple SIM profiles on a single SIM card, allowing both types of SIM to benefit from automatic switching based on the best available signal or predetermined criteria such as cost or network preference.

Differences

Beyond their shared features, here’s what distinguishes multi-IMSI SIMs from e-SIMs: 

Removability 

Multi-IMSI SIM cards are physically removable, fitting traditional SIM card slots. Conversely, e-SIMs are often “embedded,” or soldered directly onto the device's circuit board, though removable e-SIM options do exist.

MNO ties

Multi-IMSI SIMs typically have one primary MNO that manages the SIM. e-SIMs are not inherently tied to a single MNO, allowing IoT devices to switch providers without physical SIM swaps.

Carrier flexibility

With multi-IMSI SIMs, the preloaded carrier profiles cannot be altered once deployed. e-SIM technology allows for the remote downloading of new carriers, offering more control over network selection and management.

Profile management

Multi-IMSI SIMs keep all profiles active, which may not always be efficient. e-SIMs introduce the capability to activate or deactivate profiles as needed, optimizing operational efficiency and connectivity costs.

Cost management 

The always-active nature of profiles on multi-IMSI SIMs means paying for all, regardless of use. With e-SIMs, however, you only pay for the single profile in use. Additionally, multi-IMSI SIMs incur recurring fees for each active profile. In contrast, e-SIMs typically involve a one-time fee for profile provisioning.

Security and standardization

Multi-IMSI SIMs suffer from a lack of standardization, which can pose security risks. However, e-SIMs adhere to a standardized solution by GSMA for provisioning, ensuring a higher level of security and interoperability across devices and networks worldwide.

Should you use a multi-IMSI SIM?

To decide whether to use a multi-IMSI SIM for your connectivity needs, evaluate your specific requirements, the geographic scope of your device deployment, and your desired level of network flexibility. Factors such as carrier support, profile management, and security implications are crucial in this decision-making process. Before settling on a global SIM solution, weighing a few notable drawbacks of multi-IMSI SIMs is essential.

Limited carrier support

Multi-IMSI SIMs lack support from major carriers, especially within the United States. This limitation means devices equipped with multi-IMSI SIMs might be unable to access the networks of significant US carriers, severely restricting their operational utility in one of the world's largest markets. In contrast, e-SIMs are gaining widespread acceptance among major carriers globally, including those in the US, providing broader and more flexible network accessibility.

Always active profiles

Multi-IMSI SIMs inherently maintain all profiles in a constant state of readiness, leading to inefficiency by keeping network connections active regardless of actual usage.

On the other hand, e-SIM technology introduces the option to deactivate unused profiles. This deactivation feature conserves essential network resources and bolsters security by limiting the active attack surface. It also facilitates more efficient, cost-effective roaming and network management strategies by eliminating the need to maintain all profiles in an active state.

Lack of remote provisioning

The inability to provision profiles remotely on multi-IMSI SIMs presents a logistical challenge, particularly for devices deployed across different countries or in hard-to-reach locations. The e-SIM enables on-the-fly adjustments to network access and carrier changes without physical access to the device, significantly enhancing operational flexibility and efficiency.

Security vulnerabilities

Multi-IMSI SIMs are less secure than e-SIMs due to the lack of a standardized security framework and the increased complexity of securely managing multiple network identities. e-SIMs address these issues through advanced encryption, secure provisioning, and global standardization. In contrast, e-SIMs offer sophisticated encryption and secure remote provisioning, reducing the risk of unauthorized access and making them safer for sensitive or critical IoT deployments.

Connectivity issues due to constant profile switching

With multi-IMSI SIMs, the continuous switching between profiles to maintain connectivity in different regions can cause interruptions and degrade the quality of service. e-SIMs mitigate this issue by providing smoother transitions between networks and the ability to select the most appropriate profile for a given area without constant switching, ensuring more stable and reliable connectivity.

Given these considerations, e-SIMs often present a more advantageous solution over multi-IMSI SIMs, offering improved network support, flexibility in profile management, enhanced security, and more stable connectivity, making them a preferable choice for many IoT applications.

A single global SIM as an alternative to multiple IMSIs

Global roaming SIMs present a compelling alternative to multi-IMSI SIMs and eUICC SIMs. Like multi-IMSIs and e-SIMs, global roaming SIMs connect to the best available network in any region without requiring manual SIM swaps. However, these SIMs achieve global connectivity through an MVNO’s strategic partnerships with carriers across the world rather than through multiple IMSIs. 

Global roaming SIMs provide a more straightforward approach to achieving international coverage. Unlike multi-IMSI SIMs, which require pre-loaded carrier profiles, global roaming SIMs eliminate the complexity of handling numerous IMSIs by relying on a single SIM that can seamlessly roam across an extensive network of carrier partners. 

While eUICC SIMs use provisioning to manage profiles for each carrier, global roaming SIMs bypass this requirement, offering an out-of-the-box solution that can immediately access a wide range of networks. This can be particularly advantageous for IoT applications that require rapid deployment and minimal management overhead.

Zipit's global SIM delivers expansive connectivity across more than 160 countries. Its ability to support permanent roaming, along with its adaptability to various cellular technologies—from LTE Cat-M1 and NB-IoT to 5G—reliably meets a variety of IoT needs. We manage roaming to avoid high-cost areas and regions with roaming constraints, ensuring cost efficiency and adherence to regulatory standards.

Connect anywhere with Zipit

At Zipit, we believe connectivity should be seamless, secure, and scalable, regardless of your IoT projects' geographic or operational scale. Our direct relationships with leading MNOs give our partners the flexibility to manage carrier connectivity across our network of supported carriers without the need to initiate new contracts or navigate the complexities of carrier negotiations. Should you decide to switch carriers, our arrangement eliminates the hassle of canceling existing contracts, offering agility that is rare in the cellular industry.

Zipit provides a connectivity management platform that integrates seamlessly with our diverse SIM solutions to provide a centralized hub for managing all your connectivity needs. This platform simplifies the activation, management, and monitoring of devices and SIMs and grants real-time insights into connectivity and usage patterns. 

Partnering with Zipit goes beyond choosing a connectivity provider; it means partnering with a team committed to the success of your IoT solutions across all regions. With our direct MNO relationships, tailored SIM solutions, and sophisticated connectivity management platform, you can handle the intricacies of global IoT connectivity, facilitating successful deployments and efficient operations and keeping your devices connected wherever they’re located. 

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