However, global roaming comes with technological risks. Each local operator (MNO) in a given country uses its own network core, its own configurations, and may carry out equipment upgrades at any time — upgrades that can affect the operation of roaming partners.
The compatibility problem: equipment from different vendors may handle the exchange of signaling messages differently. What was “forgiven” by legacy systems can become a critical error after the host network’s infrastructure is updated. The story of our protagonist — a roaming eSIM operator — is the best proof of this.
The Incident: Network Upgrade in Australia
It all started with complaints from tourists in Australia. Subscribers reported a complete lack of mobile internet despite being registered on the network. The operator’s technical support checked balances, eSIM statuses, and device settings — everything appeared to be in order.
The investigation revealed the true cause. The local Australian operator (MNO) had carried out a planned network upgrade. As part of the upgrade, legacy 3G networks were shut down, but problems also began appearing in the 4G band.
Investigation: The Problem in GTPv2 Signaling
The roaming operator’s legacy PGW (Packet Data Network Gateway) failed this check. Upon receiving a Create Session Request from the Australian side, it generated a Create Session Response containing parameters that did not meet the updated requirements. The Australian network, following its standards, discarded such responses, and the connection could not be established. Subscribers could see the network but were unable to access the internet even on modern 4G.
The Saving Solution: VAS Experts’ PGW Steps In
At this critical moment, the operator had a test bench deployed using VAS Experts solutions. The engineers made a decision: switch the problematic Australian interconnect from the legacy PGW to the Stingray PGW by VAS Experts being evaluated, and verify operation using test subscribers.
The result exceeded expectations. The connection was established instantly.
Unlike the legacy equipment, Stingray PGW strictly adheres to 3GPP standards and GTPv2 protocol specifications. It generated a correct Create Session Response that fully satisfied the requirements of the Australian operator’s updated network. Test subscribers connected to the new core successfully gained 4G internet access.
Outcome: Tourists Back Online
Stingray PGW restored connectivity and helped identify the root cause of the problem — incorrect operation of the legacy PGW at the signaling level. Subscribers received stable 4G internet, and the product proved its compliance with international standards in a real-world production scenario where the legacy solution had failed.
Technical Details
The success of this case is explained by the architectural features of the VAS Experts solution:
- Strict 3GPP compliance: VAS Experts’ PGW is developed in accordance with all current specifications. It does not allow loose interpretation of protocols, which is critically important when interacting with major operator networks that apply strict validation of signaling traffic.
- Correct GTPv2 stack handling: The gateway correctly processes all Information Elements (IEs) in Create Session Request messages and generates valid Create Session Response replies, ensuring successful session establishment even after equipment upgrades on the partner’s side.
- Multi-access support: The PGW supports operation across 3G, 4G/LTE, and 5G networks within a single device.
It is worth noting that a PGW often has built-in PCEF (Policy and Charging Enforcement Function) functionality. The built-in PCEF allows flexible traffic billing in roaming and the application of QoS policies. In our architecture, the PGW can operate as a standalone unit or in conjunction with a proprietary PCEF.
Conclusion: From Testing to Production
The successful resolution of the Australian incident became a turning point. The eSIM operator, having confirmed the reliability of the VAS Experts PGW, decided to deploy the vendor’s equipment into full production.
This case clearly demonstrates the key requirement of the modern roaming market: the network core must be ready for any surprises from the many host network operators around the world, strictly adhere to standards, and keep pace with the times — so that no partner network update ever affects the availability of the service to subscribers.
