Multi-IMSI vs Multi-core SIMs: Which protects your IoT?

Multi-IMSI and eUICC SIMs both promise multiple providers on one card to give businesses greater control and flexibility. But, how do they differ, and which solution best protects your connectivity?

It's simply not realistic to replace SIMs in IoT devices every time you need a new network provider. Not only are devices often widely dispersed or located in remote areas, the fees associated with SIM swaps aren't reasonable for growth-mode companies. This reality led to the creation of multi-IMSI and eUICC SIMs, promising multiple providers on one card to give businesses greater control and flexibility with their provider choices.

While multi-IMSI SIMs offer an advantage over traditional SIMs, they fall short in fully protecting your connectivity in the event of a major outage. That's why Hologram created its Outage Protection SIMs, designed to deliver the industry's first truly fail-safe connectivity with a multi-core SIM.

In this article, we'll break down how Multi-IMSI, eUICC, and Outage Protection SIMs differ and help you determine which technology best fits your business needs.

Key takeaways

• Multi-IMSI SIMs store multiple carrier profiles on one card but are pre-programmed at manufacturing and cannot be updated remotely, limiting flexibility for deployed IoT devices.
• eUICC SIMs allow over-the-air profile updates but share the same single point of failure as Multi-IMSI SIMs. When the underlying mobile core goes down, all profiles become inaccessible.
• Hologram's Outage Protection SIMs connect through two independent mobile core networks with automatic failover technology, eliminating the single point of failure that affects both Multi-IMSI and eUICC solutions.
• Outage Protection SIMs provide access to 550+ carriers across 190+ countries and automatically switch profiles when downtime occurs, while Multi-IMSI and eUICC require manual intervention during outages.

What is a Multi-IMSI SIM?

A Multi-IMSI SIM stores multiple International Mobile Subscriber Identities (IMSIs) on a single physical SIM card, allowing devices to switch between carrier profiles based on network availability or cost. This makes them a cost-saving solution for devices requiring international roaming.

Key characteristics of Multi-IMSI SIMs:

• Local IMSI switching: Avoid roaming charges by switching to a local carrier profile
• Pre-programmed profiles: IMSIs are set at manufacturing—no over-the-air updates
• Single core dependency: All profiles route through one mobile core infrastructure

However, Multi-IMSI SIMs are pre-programmed at manufacturing. Businesses can't dynamically add new operator profiles without physical access to the device which is a significant limitation for deployed IoT fleets.

What is an eUICC SIM?

eUICC (Embedded Universal Integrated Circuit Card) SIMs store and manage multiple carrier profiles on a single SIM—with the added ability to update profiles remotely over the air.

eUICC capabilities include:

• Remote profile management: Download, update, or delete carrier profiles without physical access
• Regional flexibility: Adapt to different network conditions across geographies

Despite this flexibility, eUICC SIMs share a critical flaw with Multi-IMSI: a single point of failure .

Why Hologram's Outage Protection SIM is the next leap forward

Hologram's Outage Protection SIMs eliminate the single point of failure by connecting through two completely independent mobile core networks. If one network goes down, your devices stay online through the other.

Unlike Multi-IMSI or standard eUICC solutions, Outage Protection SIMs include automatic Fallback technology that continuously monitors your connection and switches profiles the moment downtime occurs.

How Outage Protection SIMs differ from multi-IMSI and eUICC:

• More paths to connectivity: Even if one major network goes down, you'll have the ability to connect to another entirely different set of providers.
• Automatic Fallback tech: In the past, businesses would need to switch between networks on their own. With Hologram's Fallback, our software regularly monitors your connection and switches your device when downtime occurs.
• Comprehensive, global coverage: Access to 550+ carriers in 190+ countries simply gives you more options than pre-programmed IMSIs, providing dependable coverage no matter where your devices are located.

Multi-IMSI vs. eUICC vs. Outage Protection SIMs

While all three SIM technologies store multiple carrier profiles on a single card, the differences in how they manage connectivity can mean the difference between minor inconvenience and catastrophic downtime. Multi-IMSI SIMs are locked into their pre-programmed profiles at manufacturing. While eUICC adds the flexibility of over-the-air profile management, both share a critical weakness.

Only Outage Protection SIMs eliminate the single point of failure by connecting through two completely independent mobile core networks with automatic Fallback technology that switches profiles the instant downtime is detected, ensuring your devices stay online even when a major network outage takes down an entire core infrastructure.

The choice that's right for you

To determine the right fit, evaluate your downtime risk and the level of protection your business requires. Our e-book Up and running: The guide to eliminating IoT downtime can help.

Frequently asked questions

What is the difference between SIM and IMSI?

A SIM is the physical card that stores subscriber data, while an IMSI (International Mobile Subscriber Identity) is the unique identifier stored on that SIM that authenticates your device to a mobile network.

What does multi-IMSI mean?

A Multi-IMSI SIM stores multiple International Mobile Subscriber Identity profiles on one physical card, allowing devices to switch between different carrier networks based on availability or cost.

What is the difference between eSIM and multi-IMSI?

eSIM (eUICC) technology allows remote over-the-air updates to carrier profiles, while Multi-IMSI SIMs are pre-programmed at manufacturing and cannot add new profiles without physical access to the device.

What are the three types of SIM cards?

The three main SIM types are physical SIM cards (removable chips), eSIM (embedded, remotely programmable), and dual-SIM (devices that support two active SIM profiles simultaneously).