What Is a Fixed IP SIM Card – and Do You Need One?

The problem a fixed IP SIM solves

Most SIM cards work the same way. Your device connects to the mobile network and gets assigned an IP address from a shared pool. When it disconnects and reconnects – after a reboot, a network handover, a power cut – it gets a different address. That’s fine for the majority of devices on the internet. It’s a problem the moment something else needs to reach your device at a known, predictable address.

Think about what that looks like in practice. An engineer at a desk needs to log into a router at a remote pumping station. A SCADA platform needs to poll equipment at a substation every thirty seconds. A CCTV management server needs to pull footage from cameras at a retail park. In every one of those cases, the system initiating the connection needs to know where to find the device – and a dynamic IP that changes unpredictably makes that impossible to manage reliably.

A fixed IP SIM solves this cleanly. The same address is assigned to your SIM every time it connects, which means remote systems, monitoring platforms and access tools always know where your device is.

What a fixed IP SIM actually costs in the UK

There’s a meaningful price difference between the two approaches to stable, reachable IP addresses – and it’s worth understanding why before making a decision.

Fixed public IP SIM cards start from £12.00 per month ex VAT. Each card needs a dedicated, permanently assigned public IP address. IPv4 addresses are a finite resource, and holding one against a single SIM indefinitely carries a cost that a dynamic SIM doesn’t. That price reflects the provisioning involved, not a margin decision.

Private IP SIM cards with VPN access start from £2.20 per month ex VAT – the same entry price as a standard roaming SIM. These give you stable inbound access through an encrypted tunnel. The address is private, not publicly routable, which means it isn’t visible to internet scanning. For a large proportion of deployments – remote router management, CCTV viewing, SCADA access – this is the better option technically and the cheaper option commercially.

The right question to ask is not which is cheaper, but which suits how your system is built. If you control both ends of the connection and can configure a VPN client, private IP is almost always the right call. If a third-party platform needs to reach your device directly on a public address with no VPN in the path, fixed public IP is what you need.

When you actually need a fixed IP – real deployment examples

The clearest way to understand when a fixed IP SIM is the right choice is to look at what the deployments actually look like.

Remote monitoring and SCADA

A water treatment operator runs thirty unmanned pumping stations across a county. Each site has a Teltonika RUTM52 router on a cellular connection. The SCADA platform at the control centre needs to poll each site’s PLCs every minute via DNP3. The platform vendor doesn’t support VPN tunnels – it needs a direct IP address for each site. Fixed public IP SIMs, one per router, with inbound access restricted by source IP on the router firewall. Read more about SIMs for SCADA and remote monitoring.

CCTV and security systems

A security installer manages cellular CCTV at forty car parks. Their central management platform connects inbound to each NVR to pull footage and check health. The NVRs don’t support VPN client configuration. A fixed public IP SIM in the router at each site, port forwarding to the NVR, access restricted to the management platform’s IP range. Straightforward, and the right tool for the job. More on SIMs for CCTV systems.

Remote router management – where private IP wins

An IT manager looks after 4G routers at fifteen branch offices. He needs to be able to log into each router remotely to check configuration and push firmware updates. He controls the management laptop, and all the routers support IPsec and OpenVPN. Private IP SIMs with VPN configured on each router – he connects via VPN tunnel, the routers are completely invisible on the public internet, and his monthly SIM spend is a fraction of what fixed public IP would cost. This is the scenario where the instinct to buy fixed public IP SIMs is understandable but wrong.

Fleet tracking and asset management

A logistics operator runs vehicle tracking hardware across a fleet of 200 HGVs. The tracking units report outbound to a cloud platform – GPS position, engine data, driver behaviour. No inbound connection is ever needed. Standard dynamic IP roaming SIMs across the whole fleet. Fixed IP would add cost with no benefit whatsoever.

EV charging and smart metering

A charge point operator needs remote management access to EV chargers at a retail site. The charger management system initiates connections back to the hardware. If the management system supports OCPP over VPN, private IP is fine. If it expects a direct IP address per charger – which some older implementations do – fixed public IP is the route. Worth confirming with your platform vendor before ordering SIMs. More on SIMs for EV charging.

Can you get a static IP with 5G?

Yes – and it works exactly as you’d expect. Fixed and private IP SIM cards work on 5G in the same way they work on 4G. The IP assignment happens at the network level, tied to your SIM and APN configuration. The access technology – 4G, 5G, even 3G as a fallback – doesn’t affect it. If your hardware connects on 5G, it presents the same fixed or private IP it would on any other generation.

The practical caveat is that most IoT and industrial deployments in the UK are still primarily 4G. 5G coverage outside city centres remains inconsistent, and the routers deployed at field sites – substations, pumping stations, remote industrial plant – are often chosen for ruggedness and 4G reliability rather than 5G capability. That’s changing, but slowly.

Where 5G does matter is in bandwidth-intensive applications – high-definition CCTV with multiple streams, large data transfers, or sites where 4G capacity is constrained. If you’re specifying 5G-capable hardware like a Teltonika RUTM55 or a Milesight UR75 and want a fixed or private IP SIM alongside it, all our SIMs include UK mobile network roaming and will connect on 5G where it’s available. The IP assignment works the same either way.

Which SIM type is right for your deployment?

The decision comes down to one question: who initiates the connection, and can they use a VPN?

If your device only sends data outward and is never called into from outside, a dynamic IP roaming SIM is the right and cheapest option. If something outside needs to reach your device and you control both ends, private IP with VPN is usually the better and more secure answer. If a third-party system needs a direct public address with no VPN in the path, fixed public IP is what you need – and it’s worth pairing that with the hardening steps in our router security guide, since a public static address will be found by internet scanners.

If you’re not sure which applies to your setup, that’s exactly the conversation to have before ordering. Tell us what you’re connecting, how your management platform or remote access tool works, and we’ll give you a straight recommendation.

Read our full fixed vs dynamic IP guide for a more detailed side-by-side comparison including a summary table and worked examples.