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What is an IoT SIM card?

An IoT SIM card connects devices to the internet over cellular mobile networks.

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True Multi-Network
No PLMN restrictions
Remote Steering
Switch networks post-deployment
Private APN & Fixed IP
Secure, isolated traffic
Flexible PAYG
No contracts or minimums

Unlike consumer SIM cards which are designed for phones, IoT SIMs are built for long-term deployments where reliability, remote management and predictable costs matter.

They are commonly used in routers, CCTV systems, payment terminals, telemetry devices, alarms, vehicle tracking systems and industrial equipment mainly for low volume data but in some cases can utilise voice and SMS.

The network architecture behind the SIM is a major driver of coverage, performance and longevity.

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KeySIM IoT SIM Card

The Four Types of IoT SIM Cards

Not all IoT SIMs work the same way. Understanding how each type selects a network — and where they break down — is the difference between a deployment that "just works" and one that fails on weak signal.

01

Single-Network IoT SIMs

One network only — best for high-data, fixed installations

Single-network IoT SIMs connect to one mobile network only. In areas with strong signal from that network they can work very well, particularly in fixed installations with high monthly data usage.

They are often used in applications consuming large amounts of data because pricing can sometimes be more cost effective than multi-network connectivity.

The downside is that if the network experiences congestion, maintenance issues or weak signal in a specific area, the device has no alternative network available.

Watch out for consumer SIM terms.

When procuring single network SIM cards for connected machines it is prudent to verify the contractual terms cover IoT as business use and resale can be prohibited. For example, giffgaff states its services are intended for "private, Personal Use and non-commercial purposes", while Three UK states resale is not permitted unless the customer becomes an approved Three reseller.

02

Steered Multi-Network SIMs

Multiple networks with a preferred-network list (PLMN)

Steered multi-network SIMs can access more than one mobile network but use a preferred network list (PLMN) to prioritise certain operators.

PLMN lists are described in detail in the 3GPP TS 23.122 document.

This approach is commonly used to reduce roaming costs while still allowing fallback access to alternative networks if the preferred network is unavailable.

In many deployments this works well, but problems can occur when the preferred network still has a weak usable signal. In these situations, the modem may continue trying to use the prioritised network even when another available network would perform significantly better.

03
KeySIM core offering

Unsteered Multi-Network IoT SIMs

No PLMN list — the device picks the strongest signal in real time

Unsteered multi-network SIMs do not use a preferred network list. Instead, the modem is free to select from all available mobile networks based on signal conditions and standard 3GPP network selection behaviour.

This gives the router or device greater control over network selection and can improve resilience in areas where signal conditions regularly change.

At KeySIM, the average monthly usage across our multi-network SIM deployments is around 800 MB per SIM, making this type of connectivity well suited to remote infrastructure, backup connectivity and business-critical IoT applications where uptime is more important than achieving the absolute lowest cost per gigabyte.

KeySIM offers unsteered connectivity across 400+ networks through official IoT agreements with Tele2 IoT.

04
KeySIM core offering

Manually Steerable Multi-Network IoT SIMs

Remotely pin a SIM to a specific network — no site visit required

Some multi-network IoT SIMs allow devices to be remotely pinned to a specific mobile network at SIM level. This makes it possible to override the modem's automatic network selection behaviour without requiring physical access to the router or device.

This can be useful in deployments where signal conditions, congestion or network performance change over time, particularly in remote or difficult-to-access locations.

KeySIM supports remote network steering directly through the KeySIM portal, allowing users to remotely pin devices to available mobile networks without reconfiguring hardware on site. This capability was independently covered by Mobile News following KeySIM's partnership with Wired Broadcast.

Case study — HFM SmartFarm

"We spent weeks trying to get the machine connected and couldn't understand why it wasn't working, especially as we'd been told the SIM was multi-network. It just wouldn't establish a reliable connection.

After speaking to KeySIM, we tried one of their SIMs and it connected straight away. There was nothing else to change — it just worked. It resolved the issue immediately."

Tim Crombie Managing Director, HFM SmartFarm

Internet Breakout Infrastructure

Internet breakout architecture determines where traffic leaves the mobile network and reaches the internet or private infrastructure. Some providers use direct mobile operator breakout, while others use privately managed breakout infrastructure.

When private breakout is used, IoT SIM performance becomes dependent on the routing, resilience, latency and availability of the breakout platform and underlying datacentre infrastructure.

KeySIM operates UK-based network infrastructure with direct management of routing, performance and support. Traffic breaks out through multiple Tier 1 datacentre locations including Equinix facilities in Manchester, Leeds and London through FAELIX.

KeySIM is a registered RIPE NCC member operating Autonomous System AS207652 with allocated IP address space and independent routing control.

RIPE NCC Member AS207652 — independent routing control
Tier 1 Datacentres Equinix Manchester, Leeds & London via FAELIX
Tele2 IoT Partnership Official agreement covering 400+ global networks
UK-Based Operations Routing, performance and support managed in the UK

Fixed IP Connectivity Through Private Breakout Infrastructure

KeySIM fixed IP services are delivered through private breakout infrastructure designed for industrial IoT and remote access applications. Rather than relying on heavily shared public mobile internet routing, compatible deployments can maintain consistent addressing for VPN connectivity, telemetry and secure remote device access.

The quality of the breakout infrastructure can directly affect latency, routing consistency and long-term connectivity stability across IoT deployments.

Real-world examples of fixed IP connectivity in industrial environments can be seen in smart surveillance and remote monitoring deployments such as this Teltonika smart city video surveillance deployment.

Fixed IP SIM
Fixed IP IoT SIM for industrial remote access and surveillance

Industrial eUICC IoT SIM Cards

Unlike standard IoT SIM cards, eUICC-enabled industrial SIM cards can be remotely re-provisioned to an alternative mobile operator without physically replacing the SIM.

Standard IoT SIMs are normally tied permanently to a single operator profile for the life of the deployment. eUICC technology allows approved network profiles to be securely downloaded or replaced over the air. This gives businesses greater long-term flexibility and reduces supplier lock-in across large deployments.

eUICC is particularly valuable in long-life industrial installations where physical access to devices may be difficult or expensive. It is increasingly used within industrial routers, telemetry equipment, remote monitoring systems and critical infrastructure where operational continuity is important.

KeySIM supports industrial-grade eUICC IoT SIM cards for deployments requiring remote provisioning capability and long-term network flexibility.

Industrial eUICC IoT SIM with remote provisioning across global networks

IoT SIM — Frequently Asked Questions

An IoT SIM card connects devices to the internet over cellular mobile networks. Unlike consumer SIMs designed for phones, IoT SIMs are built for long-term deployments where reliability, remote management and predictable costs matter. They are commonly used in routers, CCTV systems, payment terminals, telemetry devices, alarms, vehicle tracking systems and industrial equipment.

Steered multi-network SIMs use a preferred network list (PLMN) to prioritise certain operators, which can hold a device on a weak signal even when a stronger network is available. Unsteered SIMs have no PLMN list, so the modem freely selects the strongest network at any time using standard 3GPP behaviour.

An eUICC (sometimes called eSIM) is an industrial SIM card that can be remotely re-provisioned to an alternative mobile operator over the air, without physically replacing the SIM. It is particularly valuable for long-life industrial deployments where physical access is difficult or expensive.

Internet breakout is the point where mobile data traffic leaves the cellular network and reaches the public internet or private infrastructure. KeySIM operates UK-based private breakout through Tier 1 datacentre locations including Equinix Manchester, Leeds and London via FAELIX, with independent routing as a RIPE NCC member (AS207652).

No. KeySIM operates on a flexible PAYG basis with no minimum terms. SIMs can be activated, paused or stopped as needed without long-term commitment, and dormant SIMs are not purged from the network. View PAYG pricing.

Yes. KeySIM SIMs can be remotely pinned to a specific UK mobile network at SIM level via the KeySIM portal — without any physical access to the device.

A private APN (Access Point Name) creates an isolated network for your devices, keeping traffic off the public internet. This improves security and enables remote access via VPN using private IP addresses. Learn about Fixed IP SIM.

Get Started with KeySIM IoT SIM

If your deployment relies on connectivity, you need a SIM that won't fail. Speak to our team or request your trial SIMs today.

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