This article explains what to expect during Phase 3 of the KPN mobile core network upgrade.
These changes are only relevant for customers using KPN SIMs.
If your devices do not use KPN SIMs, you can safely disregard this information.
Why this change is happening
KPN is upgrading its mobile core network to improve performance, stability, and network resilience.
Phase 3 focuses on migrating data services to KPN’s new infrastructure.
These changes will help reduce downtime risk, simplify IP management, and prepare the network for future growth.
When the migration is happening and what is the impact
Phase 3 is being carried out on an APN-by-APN basis. This phased approach helps minimise risk and ensures network behaviour is validated as the rollout progresses.
Customers may experience a temporary service interruption of approximately 10–30 minutes per APN while the work is carried out.
Devices should automatically reconnect within a few seconds or minutes after migration. If a device does not recover automatically, a manual reboot may be required.
The planned migration schedule is outlined below. Customers will receive advance communications ahead of their specific migration window by on their APNs, including confirmation of timings and any expected service impact.
Planned migration schedule by APN:
arkessa.com
Phase 3 migration: 24 February 2026 at 18:00 UTC
arkessahd.com
Phase 3 migration: 5 February 2026 at 18:00 UTC
wlapn4.com
Migration Batch 1: 27 January
Start time: 19:00 (18:00 UK time)
Estimated window: up to 2 hours
Migration Batch 2: 29 January
Start time: 19:00 (18:00 UK time)
Estimated window: up to 1.5 hours
wlapn.com
Expected to migrate in February 2026 and will be the final APN to transition as part of Phase 3. Further details, including confirmed timings, will be shared with customers in advance.
What is changing
Improved network resilience
- KPN is introducing automated failover across multiple gateways, replacing the old manual failover setup.
- This will help reduce the risk of downtime and improve continuity of service.
Fixed IP addressing changes
- Devices will no longer retain a fixed IP address at the device level.
- Instead, each device will now receive a private dynamic IP.
- KPN will apply an IMSI-based NAT function, which ensures that:
- The external-facing IP (seen by backend systems) remains unchanged.
- The local IP seen by the device will now differ, this is expected and correct.
Why this matters for your configuration
If your device or application is hardcoded to expect a fixed SIM IP, it will no longer connect correctly after migration.
Common examples include:
- VPN tunnels that use a static SIM IP as the source address.
- Applications or servers that reference a fixed SIM IP directly.
👉 For detailed step-by-step guidance on how to check your configuration and remove any hardcoded IPs, see:
- Ensuring Your Teltonika Routers with KPN SIMs Do Not Use a Hardcoded IP Address
-
Ensuring Your Devices with KPN SIMs Do Not Use a Hardcoded IP Address
What you need to do
To avoid any disruption during or after the migration, please review your setup now:
- ✅ Check whether a fixed SIM IP is hardcoded in your device or application logic. If so, it must be removed.
- ✅ Ensure all devices use DHCP (dynamic IP assignment).
- ✅ If using IPSec VPNs, set the source IP as the WAN interface, not a static SIM IP.
- ✅ Be prepared to reboot devices if they do not automatically reconnect after migration.
Updating configurations now will help you avoid unnecessary downtime and ensure a smooth transition.
Understanding the new IP behaviour
After migration, you may notice that the IP address displayed in SIMPro is different from the IP address visible on your device.
This is intentional and caused by KPN’s IMSI-based NAT function:
- The device receives a private dynamic IP locally.
- The backend system continues to recognise the same external-facing IP.
| Behaviour | Description | Action |
|---|---|---|
| ✅ Expected | The IP address shown in SIMPro differs from the IP shown on the device. | This confirms the NAT function is working correctly. No action needed. |
| ⚠️ Unexpected | The IP address shown in SIMPro is the same as the IP shown on the device. | This indicates a possible hardcoded configuration or DHCP issue. Check and update your device configuration. |
What happens if you do nothing
If a fixed IP remains hardcoded in your device or application, it may:
- Fail to reconnect automatically after migration.
- Be unable to establish VPN tunnels.
- Stop sending or receiving data.
To prevent this, please confirm your devices are correctly configured before the migration takes place.
Support and further information
- You will receive planned maintenance notifications before your specific migration window.
- Real-time updates will also be available via the SIMPro MNO Outages page.
- Our Network Operations Team is available to provide guidance on reviewing or updating your setup at support@wirelesslogic.com.
- For Enterprise customers, our Care team will provide direct support throughout the transition.
If you have any questions or need help, please contact support@wirelesslogic.com or your account manager.