Best IoT SIM guide: how to choose the right SIM for your devices

Every connected device needs a path to the internet, and for most fleets that path runs over cellular networks. The Ericsson Mobility Report IoT forecast puts cellular IoT connections at about 4.5 billion at the end of 2025. Ericsson expects that number to reach about 7.8 billion by 2031.

With so many devices coming online, picking a SIM can feel like a big bet. The good news is that the best IoT SIM is simply the one that fits your devices, markets, and uptime needs. This best IoT SIM guide walks you through each choice in plain terms.

Key takeaways

• Fit beats brand: The best IoT SIM card matches your devices, markets, and uptime needs, so define your deployment before you compare vendors.
• eUICC adds flexibility: An eUICC SIM can download, update, or delete carrier profiles remotely, so you can change networks without touching devices.
• Core redundancy matters: Multi-carrier SIMs can still share one mobile core, which leaves a single point of failure for the whole fleet.
• Coverage is more than a country count: Check which carriers and network types work in each market, and how long they will stay on.
• Total cost beats data rate: Fees for activation, suspension, profile switching, and minimums can outweigh a low price per megabyte.

What makes an IoT SIM the best choice

The best IoT SIM keeps your devices connected wherever they operate, at a predictable cost, with tools to manage them remotely. For most fleets, that means a multi-carrier SIM with remote provisioning, strong uptime protection, and pricing that fits how your devices use data.

A SIM (subscriber identity module) is the small chip that lets a device join a cellular network. An IoT SIM does the same job for machines like sensors, trackers, and meters.

IoT SIMs differ from the SIM in your phone in four main ways:

• They connect to multiple carriers, so a device can switch when one network is weak
• They let you activate, pause, and monitor SIMs remotely, with no person at the device
• They come in rugged versions built for heat, cold, moisture, and vibration
• They use plans designed for many devices sending small or steady amounts of data

So "best" depends on your deployment. A tracker that crosses borders needs different things than a smart meter that never moves.

IoT SIM form factors

A form factor is the SIM's physical size and shape. Our full guide to IoT SIM form factors goes deeper, but these are the main options.

Removable SIMs come in second, third, and fourth form factor sizes (2FF, 3FF, and 4FF), known as mini, micro, and nano. Industrial SIMs use the same sizes with tougher materials. Machine form factor 2 (MFF2) SIMs are chips soldered straight onto the circuit board.

Many buyers mix up two terms. People often say "eSIM" to describe the soldered shape, but remote profile updates come from eUICC (embedded universal integrated circuit card) software. A soldered SIM may lack eUICC, and a removable SIM can have it, so ask about both.

SIM technologies: traditional, multi-IMSI, eUICC, and multi-core

Form factor is the SIM's shape. Technology is how the SIM picks and joins networks.

The four main types below run in order of flexibility and resilience.

Traditional single-profile SIMs

A traditional SIM holds one profile. A profile is the set of credentials that tells a network who the device is and which carrier account it belongs to.

This setup is simple and works well for fleets that stay in one market with one carrier. The tradeoff is that you need to swap the physical SIM if you want to change carriers.

Multi-IMSI SIMs

IMSI stands for international mobile subscriber identity, the number a network uses to identify a SIM. A multi-IMSI SIM stores several IMSIs, each tied to a different carrier deal, and switches between them for cost or coverage.

The limits come from how these SIMs are built. Multi-IMSI SIMs are pre-programmed, so nobody can add new operator profiles without physical access to the SIM.

We break down these limits in more detail in our comparison of multi-IMSI vs multi-core SIMs.

eUICC SIMs and the SGP.32 standard

An eUICC SIM can receive new carrier profiles over the air (OTA), meaning through the network with no hands on the device. You can download, update, or delete profiles remotely.

The GSMA, the global organisation that unites mobile operators and the wider mobile ecosystem, publishes eSIM specifications. Three of them matter most:

• SGP.02: GSMA's remote provisioning architecture for embedded UICCs, per the GSMA SGP.02 specification.
• SGP.22: GSMA's remote SIM provisioning architecture for consumer devices, per the GSMA SGP.22 consumer spec.
• SGP.32: The newer IoT standard, built for devices with no screen and limited connectivity.

The GSMA SGP.32 specification page describes "remote provisioning and management of the eUICC in IoT Network Constrained and/or User Interface Constrained Devices." The GSMA listed version 1.3 of the specification in May 2026. In plain terms, SGP.32 suits devices with weak connections or no screen.

Standards only help if your provider uses them well. As we explain in our guide to how remote SIM provisioning works, "it's not enough for connectivity providers to have 'eUICC' listed on their websites."

Ask each provider how often they complete profile swaps in the field.

Multi-core SIMs

A mobile core is the central system that checks a SIM's identity and routes its data. As our comparison above explains, many multi-IMSI and eUICC SIMs reach every carrier through one core.

That design leaves a weak spot. The same comparison notes that if the core goes down, every profile on the SIM can lose service at once.

A multi-core SIM ties its profiles to two independent cores. Hologram's multi-core SIM design uses two independent mobile core networks, so if one fails, the SIM switches to the backup.

Key criteria for choosing an IoT SIM provider

This part of the best IoT SIM guide works as a scorecard. Score each provider on every item before you compare prices.

Coverage and network types

Coverage means the carriers your SIM can use in each country. Two or more carriers per market give a device a backup when one network is weak.

Next, check network types. Long Term Evolution for Machines (LTE-M) and Narrowband IoT (NB-IoT) are low-power networks for battery devices that send small amounts of data. The GSMA Mobile IoT network launches tracker counts 129 LTE-M and 140 NB-IoT commercial networks as of its November 2025 update.

Last, ask about permanent roaming rules. Some countries limit how long a foreign SIM can stay on local networks, so confirm the provider has a plan for each market. You can check carrier coverage by country to see carriers and network types market by market.

Network sunsets and future-proofing

A network sunset happens when a carrier shuts down an older network, such as 2G or 3G, to reuse its airwaves for newer ones. Devices that only support the old network go offline.

The Global mobile Suppliers Association (GSA) tracks these shutdowns. As of the December 2025 GSA 2G-3G switch-off report, 80 of 167 operators tracked had completed 3G switch-offs. And 46 of 136 operators had completed 2G shutdowns.

Sunsets reach far beyond phones. In the US, major carriers scheduled their 3G shutdowns for 2022, according to the Federal Communications Commission (FCC). Its FCC 3G phase-out guide warns that non-phone devices, like medical devices and home security systems, could use 3G.

To future-proof your fleet, choose hardware that supports 4G LTE, LTE-M, or NB-IoT, and SIMs you can update over the air. Then a network change becomes a software task with no site visit.

Redundancy and uptime guarantees

Uptime is the share of time your devices can connect. Redundancy means having a backup path when something fails.

Ask each provider what happens when its mobile core goes down. Then ask whether its uptime number sits in a service-level agreement (SLA), which is a contract with remedies, or only on a marketing page. Ask for their historical uptime information.

Management platform and APIs

A management platform is the software you use to watch and control your SIMs. An application programming interface (API) lets your own software do the same tasks automatically.

Look for these tools:

• Real-time status for every SIM in the fleet
• Usage alerts that flag issues before costs climb
• Bulk actions to activate, pause, or change plans
• APIs and webhooks, which push event updates into your own systems
• Diagnostics that show why a device went offline

Look for a dashboard that covers connectivity data like connection status, signal quality, and usage. Your own application platform still stores and processes the data your devices create.

Security

IoT SIM security controls who can reach your devices and where their data travels. Most protections are settings you turn on with your provider.

• Private APN: A private access point name (APN) routes device traffic through a dedicated gateway, away from the public internet.
• VPN: A virtual private network (VPN) creates an encrypted tunnel between devices and your servers.
• Static IP: A static internet protocol (IP) address gives each device a fixed address your servers can trust.
• SIM-to-IMEI locking: This ties a SIM to one device's international mobile equipment identity (IMEI), so a stolen SIM won't work elsewhere.
• Data residency: Confirm the provider can route and process traffic in the regions your regulations name.

Hardware compatibility

Your SIM only works if your modem, the radio part of the device, accepts it. Modems locked to one carrier may not work with multi-carrier SIMs, as our guide to selecting IoT device hardware explains.

Check certifications too. The PTCRB certification program tests that cellular devices meet industry standards. Wireless operators set it up in 1997, and CTIA Certification administers it. Many North American carriers, including AT&T, Verizon, and T-Mobile, take part.

To unlock the full flexibility of eUICC, your modem should support short message service (SMS) in some capacity. Device-agnostic SIMs work across many modules, which keeps your hardware options open.

How IoT SIM pricing works

Most IoT data plans have two parts: a fee for each SIM and a charge for the data it uses. Any best IoT SIM guide should stress that the details decide your real cost.

These are the common models:

• Pay as you go: You pay only for the data each SIM uses, which suits pilots and low-use devices.
• Pooled data: All SIMs share one data bucket, so heavy and light users balance out.
• Fixed bundles: Each SIM gets a set amount of data each month, with overage charges past the limit.
• Committed plans: You agree to a volume or term in exchange for lower rates.

Watch for fees beyond data. Ask about activation, suspension, profile switching, and monthly minimums, because these can add up fast across a fleet.

Key features to look for in an IoT SIM

The criteria above apply to any provider. Here is how Hologram SIMs line up against them.

• Global coverage: Hologram global IoT SIMs connect to 550+ carriers in 190+ countries.
• Broad network support: Hologram supports 2G, 3G, 4G LTE, 5G, LTE-M, and NB-IoT networks.
• eUICC Hyper SIMs: Hyper SIMs come in SGP.02 and SGP.32 variants, with over-the-air profile updates.
• Reliablity: Outage Protection SIMs come with 99.95% uptime, guaranteed in the contract.
• Dashboard and APIs: The comprehensive dashboard, plus APIs, let teams monitor and control every SIM.
• Conductor SIM orchestration: Conductor SIM orchestration supports SGP.02 and SGP.32 profiles. It is in early access.
• Device agnostic: Hologram SIMs work with any device not set to a single carrier.

Best IoT SIM guide checklist: questions to ask providers

A checklist turns this guide into action. Ask every provider the same questions, then test their answers with your own devices.

Run the trial where your devices actually live. Test in basements, on rural roads, or in moving vehicles, and track connection time, data use, and dropped sessions.

The best IoT SIM is the one you can still trust years from now, after networks change and your fleet grows. Start with your devices and markets, score providers with this best IoT SIM guide, and prove the answers in a field trial.

Talk with an IoT expert