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 share a single mobile core, creating a single point of failure with dormant subscription fees for each unused profile.
• eUICC SIMs add over-the-air profile updates for flexibility, but all profiles still route through one core, leaving deployments vulnerable during major outages.
• Hologram's Outage Protection SIMs distribute traffic across independent mobile cores and data centers, with automatic failover that switches profiles the moment downtime occurs.
• Your use case determines the right SIM: video telematics fleets need low latency and centralized management, medical devices need real-time redundancy, and retail rollouts benefit from single-SKU logistics.
• SIM management through a unified dashboard and APIs lets you monitor usage, pool data, and control profiles fleet-wide without touching hardware.

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) SIMc 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.

Why this matters for multi-IMSI and eUICC

Both technologies store multiple carrier profiles, but all profiles typically route through a single mobile core. When that core experiences an outage, every profile becomes unreachable. Multi-IMSI SIMs also carry hidden costs: each dormant profile may incur subscription fees from carriers. Traffic often routes through a "home" core before reaching its destination, adding latency. Some implementations use network steering that prioritizes certain carriers over the best-performing option.

Hologram's Outage Protection SIMs solve these limitations by connecting through genuinely separate mobile core networks with automatic failover between them.

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.

Managing multi-carrier SIM profiles

Deploying multi-carrier SIMs is only half the challenge. Managing them at scale needs visibility into usage, control over profile assignments, and tools that work across your entire fleet.

Dashboard and API access

Hologram's SIM management dashboard gives you a single view of every device in your deployment. You can activate SIMs, assign data plans, monitor connection status, and troubleshoot issues from one interface.

For teams building custom integrations, Hologram's REST APIs let you automate SIM provisioning, pull usage data into your own systems, and trigger profile changes programmatically. This is especially valuable for video telematics fleets or retail rollouts where you need to onboard hundreds of devices quickly.

Pooled data plans

Instead of allocating fixed data amounts to each device, pooled data plans let you share a single data bucket across your fleet. Devices that use more data draw from the pool, while low-usage devices balance them out. This approach reduces waste and simplifies budgeting for deployments with variable data consumption, like sensor networks or intermittent video streaming.

Usage monitoring and alerts

Real-time usage monitoring helps you spot anomalies before they become problems. Set alerts for unusual data spikes, connection drops, or devices approaching their allocation limits. For mission-critical deployments like medical devices or industrial sensors, these alerts give you time to intervene before connectivity affects operations.

Fleet-wide profile control

With Outage Protection SIMs, you can push profile changes across your fleet without touching hardware. Switch carriers in a region experiencing outages, adjust fallback preferences, or update firmware for your entire deployment through the dashboard or API. This control is what separates scalable IoT operations from manual, device-by-device management.

The choice that's right for you

The right SIM technology depends on your deployment needs. Here are common use cases, what matters most for each, and what is unique about Hologram’s connectivity management platform.

Video telematics fleets

Fleet managers running video telematics need low latency for real-time footage and continuous data throughput for dashcams. These deployments also need centralized management to push firmware updates and monitor connectivity across hundreds of vehicles.

Why Hologram? Outage Protection SIMs with multi-core architecture reduce latency by avoiding the home-core routing delays common in Multi-IMSI setups. Hologram's dashboard lets you manage profiles, monitor bandwidth usage, and set alerts across your entire fleet from one interface.

High-volume retail hardware rollouts

Point-of-sale terminals, self-checkout kiosks, and payment devices need reliable connectivity from day one. High-volume rollouts also demand simplified logistics, because swapping SIMs across thousands of devices after deployment is impractical and expensive.

Why Hologram? A single-SKU SIM that works globally eliminates the need to stock region-specific cards. Both eUICC and Outage Protection SIMs support quick activation, but Outage Protection adds automatic failover to keep transactions processing even during carrier outages.

Medical devices across regions

Remote patient monitoring, insulin pumps, and diagnostic equipment cannot tolerate connectivity gaps. These devices often operate across multiple countries with varying regulatory needs and need consistent real-time data transmission.

Why Hologram? Outage Protection SIMs deliver the redundancy medical devices demand. Multi-core failover keeps devices online during network outages. Coverage across 550+ carriers helps meet regional compliance needs without deploying different SIMs for each market.

Continuous video and sensor streaming

Environmental monitoring, industrial sensors, and security cameras generate constant data streams. These applications need sustained throughput, low latency for time-sensitive alerts, and predictable costs as data volumes scale.

Why Hologram? Outage Protection SIMs with pooled data plans let you aggregate usage across devices, avoiding per-device overages. Multi-core routing optimizes for throughput and latency, keeping streams stable even during peak loads or localized outages.