Private IP Roaming SIM Cards with VPN Access

The security case for private IP

Any device with a public IP address on the internet, cellular or otherwise, will be found by automated scanning within hours of going online. This is just how the internet works – scanning ranges of IP addresses for open ports and known router admin interfaces is cheap and constant. A device behind a private IP address, reachable only through an authenticated VPN tunnel, simply doesn’t appear in that scan. There’s nothing to find.

For routers, CCTV recorders and SCADA equipment in particular, this matters because these devices often run management interfaces (web UIs, SSH, Telnet, Modbus and similar industrial protocols) that were never designed to be exposed to the public internet, even with a password. A private IP with VPN keeps that management surface off the internet entirely while still giving you full remote access.

When a public IP SIM still makes sense

We’re not dogmatic about this – public IP SIM cards are available and there are legitimate reasons to use one. Some integrations require a third party to connect directly to your device’s IP address. Some existing network designs are already built around direct IP access and changing that isn’t practical right now. If that’s your situation, we’ll supply a fixed public IP SIM and walk through hardening steps for the router: disabling WAN-side management, enforcing strong unique credentials, restricting access by source IP where possible, and keeping firmware current. Our guide to securing remote router access covers the practical steps either way.

How it works with your router

Teltonika, Milesight and most other industrial 4G/5G routers support IPsec, OpenVPN and WireGuard VPN configurations out of the box. With a private IP SIM, the router connects over the private cellular network and establishes a VPN tunnel back to your office, data centre, or a cloud-hosted VPN endpoint. Once that tunnel is up, the router – and anything connected to it, such as cameras or PLCs – is reachable exactly as if it were on your local network.

If you’re setting this up for the first time, our team can talk through VPN configuration for your specific router model alongside the SIM itself. See our private APN and VPN explained guide for more background, or jump straight to SIM cards for Teltonika routers and SIM cards for Milesight routers for hardware-specific notes.