How a private fixed IP SIM works
When the SIM connects, it joins a private APN instead of the public internet APN. The APN gives it a fixed private address from a range reserved for your devices. Traffic from the SIM travels across the mobile network into a private network that only you and your provider can reach.
To reach the devices, you connect your own network to that private network over a VPN. From then on your systems can talk to every SIM by its fixed address, as if the devices were on your office network.
Ways to connect to your private SIM network
- Site-to-site VPN. Your office firewall or data centre router holds a permanent IPsec tunnel to the private network. Staff on the office network can reach every device.
- Remote user VPN. Engineers connect from a laptop with an OpenVPN or WireGuard client, wherever they are.
- Cloud connection. The private network links to your platform in a cloud or colocation environment, so devices report straight to your servers.
Shared or dedicated private APN
A shared private APN is the quickest way to start. Your SIMs sit in their own address range and firewall zone within a private network that serves several customers, and cannot see other customers’ devices. A dedicated APN gives your organisation its own private network name, your own address plan and custom routing. It suits larger estates, organisations with their own RADIUS or addressing standards, and projects with audit requirements.
Private or public fixed IP?
Choose private when devices must never be visible on the internet, when you manage many sites, or when your security policy or a standard such as PCI DSS favours closed networks. Choose a public fixed IP when you want to reach a small number of devices from any internet connection using apps or a browser, and you are comfortable securing them with the router firewall.
If the devices also need the internet, for example to fetch updates, internet breakout can be added so that outbound traffic leaves through a controlled gateway while inbound access remains closed.
Questions we are often asked
Can anyone on the internet reach a private fixed IP SIM?
No. The address is private and the APN is not connected to the public internet, so the device cannot be scanned or attacked from outside.
Do I need special equipment to use a private APN?
No special SIM equipment is needed. You set the private APN name in the router. To reach the devices you need a VPN endpoint, which can be your existing office firewall or a software client.
Can devices on a private APN reach the internet?
Only if you ask for internet breakout. Without it, devices can only talk to your private network, which is often exactly what a security team wants.
Can I choose my own IP address range?
On a dedicated APN you can usually specify the range so it fits your existing network. On a shared APN a range is allocated to you.