SCADA, telemetry and remote monitoring equipment typically needs secure remote access without being exposed to the public internet. Private IP roaming SIM cards with VPN are our recommended option, keeping RTUs, PLCs and telemetry units reachable only via an authenticated VPN tunnel. Multi-network roaming and multi-WAN failover configurations are supported for sites where resilience is critical.
Why private IP matters for industrial protocols
Industrial control protocols such as Modbus TCP, DNP3, OPC UA and BACnet were generally designed for use on isolated networks, with limited authentication or encryption by modern standards. Exposing a device speaking one of these protocols directly to the public internet – even behind a password on the router itself – creates risk, because the protocol traffic and any management interfaces become discoverable by internet-wide scanning.
A private IP SIM with VPN addresses this by keeping the device on a private, non-routable address. Engineers and monitoring platforms connect via VPN to reach the device, exactly as if they were on the local network at the site, while the device itself is invisible to anyone scanning the public internet.
Resilience: multi-network and multi-WAN
For sites where connectivity loss has operational consequences – remote pumping stations, substations, environmental monitoring – many deployments use a router configured with multiple WAN connections for automatic failover. This might mean two SIMs on different mobile networks, or a cellular SIM backing up a fixed line. Our multi-network roaming SIMs are well suited to this: even a single SIM roams across UK mobile networks, and for maximum resilience we can supply SIMs across different operators for true multi-WAN setups.
Hardware considerations
Routers from Teltonika (including the RUTM and RUTC series for industrial deployments) and Milesight support the protocol stacks and VPN configurations commonly used in SCADA and telemetry applications, including GNSS for GPS time synchronisation where required. Our team can advise on router selection alongside SIM connectivity for your specific deployment – see our private APN and VPN explained guide for background on how the VPN side works.