The wrong SIM strategy can make or break your IoT project. Devices go dark, networks under-perform, and scaling beyond a few thousand units becomes a logistical problem.
A SIM might seem like a small piece of the stack, but it controls everything from connectivity and compliance to cost and customer experience. And once your devices are deployed – especially in hard-to-reach places – you can’t just swap them out. If your SIM isn’t built for over-the-air switching, you’re stuck.
So, the question isn’t just “Which SIM has the best coverage?” It’s: “Can this SIM survive a 10-year deployment in 20 countries without locking me in or breaking the bank?”
Why a standard SIM doesn’t work for IoT
Consumer SIMs are built for smartphones but IoT devices are different. They may:
- Transmit small data packets infrequently,
- Operate in remote, mobile, or harsh environments,
- Sleep for long periods and wake on event,
- Scale from dozens to tens of thousands of endpoints.
Core criteria: What to look for
When choosing a global IoT SIM, it pays to focus on these seven essentials:
1. Global reach with local compliance
Can the SIM connect to multiple networks in borders while complying with regional data sovereignty laws?
2. Reliable roaming
Will it connect intelligently to the best available signal, not just a single pre-selected carrier?
3. eUICC or multi-IMSI support
Does the SIM support eUICC (for remote SIM provisioning over the air) or multi-IMSI (for switching between pre-loaded profiles)? These technologies help prevent vendor lock-in and enable flexible connectivity management.
4. SIM form factors
Is the SIM available in the right physical format: embedded MFF2, industrial grade 2FF/3FF/4FF, or ruggedised versions?
5. Secure connectivity
Does it support VPNs, private APNs, IPsec tunnels, and end-to-end encryption?
6. Scalable pricing
Is the pricing aligned with how IoT devices behave: low data, long deployment lifespans, and high-volume fleets?
7. Cloud-based SIM management
Can you activate, monitor, and troubleshoot all your SIMs through a centralised, cloud-native platform?
The UK IoT SIM market
The UK hosts a mature IoT connectivity ecosystem, with major operators like BT/EE, VodafoneThree, O2 Telefónica, and specialised providers like Eseye, Wireless Logic and Truphone. Whether you’re deploying domestically or preparing for international rollout, choosing a partner with network flexibility and long-term scalability is important.
USA IoT SIM market
In the US, leading MNOs include AT&T, Verizon, T-Mobile US, and global players like Eseye, KORE Wireless and 1NCE. Each offers distinct strengths in network access, device management, and low-power wide-area technologies. What matters most is selecting a provider that matches your deployment footprint and technical requirements.
How to decide what’s best?
There’s no one-size-fits-all IoT SIM, that’s exactly a key point. The right choice depends on the specific demands of your application, device estate, and long-term business goals. To break that down, consider the following:
- Deployment geography: Are your devices roaming in borders or behind firewalls in rural municipalities? If your SIM can’t localise traffic where required (e.g. for GDPR or HIPAA compliance), expect delays or regulatory pushback.
Ask yourself: Where will my devices be five years from now and will my current SIM still work there?
- Network performance and fallback: It’s not just about connectivity availability. Some SIMs prioritise their own MNO partner even when another signal is stronger. Inconsistent connections kill uptime as well as killing trust with your customers.
Look for: Intelligent network steering, signal-based failover, and eSIM localisation, not just a spec sheet checkbox.
- Bandwidth and throughput needs: Not all IoT is low data. If you’re streaming video, running diagnostics, or managing fleets, you’ll need consistent data throughput and visibility when traffic lag.
Avoid: Providers that charge you for “bursty” data patterns or throttle peak use in multi-device rollouts.
- Hardware constraints: Device size, durability, and accessibility all impact SIM choice. For example, embedded MFF2 SIMs are ideal for devices deployed in harsh conditions or locations where physical replacement isn’t feasible.
Always: Start with the device. 80% of IoT projects fail because of an issue at the device level. If you spend time upfront getting the device right, success will follow.
- Data behaviour and pricing: Unlike smartphones, IoT devices often send kilobytes of data rather than gigabytes. Your SIM provider should understand this and offer pricing models that reflect real-world use, not overcharge for underused bandwidth.
Look for: Billing transparency and pricing models designed for IoT traffic patterns.
- Security and compliance: If you’re handling sensitive or regulated data (as in the healthcare, energy, or finance sectors), you need more than basic encryption. Look for SIMs that support VPN tunnels, private APNs, and allow for data localisation to meet local laws.
Look for: A SIM connectivity management platform that enables end-to-end data protection and regional compliance.
- Switching risk: Here’s the trap: you find a provider that works – until you grow, shift markets, or hit a price wall. Suddenly, you’re locked into a single carrier with no OTA fallback plan.
A few years ago, a US-based cashless payments company with over a million global connections learned this the hard way. When AT&T and Verizon sunset their 2G networks, the customer’s entire estate faced disconnection. A physical SIM replacement would’ve cost $24 million in truck rolls.
Instead, Eseye’s AnyNet+ SIM steered its devices to T-Mobile’s still-active 2G network using multi-IMSI technology. That bought it another year and saved ~$20 million in the process.
Fix it now: Choose eUICC-enabled SIMs with tested multi-IMSI fallback and the infrastructure to deliver OTA changes without touching a single device.
- Fleet visibility and control: Ask to see the actual SIM management dashboard before you buy. Does it show real-time diagnostics? Can your ops team query use by device, country, or IMSI? Can your devs plug it into your platform via API?
During the 2G shutdown crisis, the payments company mentioned above didn’t just rely on OTA steering – it needed granular control and insight in 1.1 million connections, a level of visibility you want from day one.
If the answer is “we’ll get back to you,” you’ve already lost control.
The bottom line
Choose a SIM that won’t lock you into a network, a region, or a pricing model. You need control, resilience, and the freedom to scale.
Start With a Free Global SIM Trial.If you want to see how an IoT SIM will work for your device, network, or region? Test it at no cost and with no commitment. Eseye’s free IoT test kit gives you everything you need to trial the AnyNet+ SIMs in real-world conditions. You’ll be able to evaluate coverage, connection reliability, failover, and platform control.
The following is included in a trial kit:
- Free AnyNet+ SIM, ready to connect with a prepaid data plan,
- Support for 2G, 3G, 4G/LTE, and LTE-M connectivity,
- Global access to 800+ networks in 190+ countries,
- Automatic network failover for built-in resilience,
- Access to the Infinity IoT Connectivity Platform™,
- Guidance on setup and best practices from IoT experts.
In 48 hours, you’ll be able to connect your device, evaluate performance, and explore data use and SIM management features. It’s the fastest way to validate whether Eseye’s global IoT platform meets your technical and business needs.
If you need to switch providers in your entire device estate, then Eseye’s eUICC-enabled SIMs and network-agnostic infrastructure let you transition without disruption in two steps.
Test before you invest. Request your free IoT SIM trial kit and start building with confidence.
