As part of the KPN Mobile Core migration (Phase 3), it is critical to confirm that your devices are not configured with hardcoded SIM IP addresses.
After the migration, devices will no longer retain a fixed IP at the device level, and any static or manual IP configuration may cause connectivity failures.
Why this matters
- Following the migration, KPN is introducing an IMSI-based NAT function.
- Each device will be assigned a private dynamic IP locally.
- NAT ensures that the external-facing IP (used by backend systems) remains unchanged, whilst the IP seen locally by the device itself will differ.
- If a fixed IP is hardcoded in your device or application configuration, it will no longer be valid after migration.
This could prevent devices from reconnecting, forming VPN tunnels, or transmitting data.
⚠️ Important: Always configure your devices to obtain their IP automatically (DHCP).
Never enter the SIMPro IP address manually.
How to check your device’s IP address
1. Use a router or device management system (if available)
If you use a router management system (e.g. Teltonika RMS, Cradlepoint NetCloud) or a device management platform provided by your hardware manufacturer, this is usually the easiest way to confirm the IP address your device is using.
- Look under Network, WAN, or Status in the management dashboard.
- The IP shown there will not match the IP displayed in SIMPro — this is expected.
2. Check directly on the device
If no management system is available, you can often view the IP address from the device itself:
- Web interface or dashboard – many gateways and modems have a built-in web page showing network status.
- Command-line interface (CLI) or serial console – some devices allow you to log in and view the current IP configuration.
3. Use AT commands (for modules and modems)
For cellular modules or USB modems, you can query the assigned IP using standard AT commands.
- Example: AT+CGPADDR returns the IP address currently assigned by the network.
4. Check from a connected host system
If the IoT device is connected to another system (such as a PC or embedded controller):
- Windows: Run ipconfig and check the cellular or WWAN adapter.
- Linux: Run ifconfig or ip addr and review the interface used by the modem or gateway.
What to look out for
- The IP address seen on your device will differ from the IP address shown in SIMPro — this is normal and confirms the NAT function is working correctly.
- Ensure your device configuration does not contain a hardcoded IP from SIMPro or any previously fixed IP allocation.
- Devices should always be set to use dynamic (DHCP) assignment.
If you cannot check locally
If your device does not provide a way to view the local IP address:
- Confirm in the device documentation that it supports DHCP or dynamic IP assignment.
- Ensure there is no configuration field containing a static or fixed IP linked to the SIM.
- If you are unsure, contact your device supplier or manufacturer for guidance.
Key reminder
After migration:
- Devices will receive private dynamic IPs.
- KPN’s NAT function ensures that external-facing IPs remain consistent for backend systems.
- The local IP visible on your device will differ from the IP shown in SIMPro.
- Any configuration relying on the old fixed SIM IP will no longer work.
✅ Expected behaviour
After the KPN migration (Phase 3):
- The IP address shown in SIMPro and the IP address visible on your device should be different.
- This difference is intentional and caused by KPN’s IMSI-based NAT function, which assigns each SIM a private dynamic IP whilst maintaining a consistent external-facing IP for backend systems.
⚠️ Unexpected behaviour
If the IP address shown in SIMPro is the same as the IP shown on your device, this likely means:
- The device has been manually configured (hardcoded) with the SIMPro IP, or
- The device is not obtaining its IP dynamically (DHCP), or
- There is a configuration issue preventing the NAT function from operating correctly.
In this case, the device may fail to reconnect or transmit data after migration.
Support
If you need help checking your device configuration, please contact our Network Team at support@wirelesslogic.com.