GTP Filter for APN Correction in GPRS Roaming
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Solution Overview
Problem
In GPRS roaming scenarios, especially with Dual/Multi IMSI and MVNO/E networks, GTP messages are often wrongly routed to sponsor operator GGSNs, leading to failed GPRS services due to automatic APN modification by smartphones, which complicates real-time charging and security, and existing solutions are either not universal or come with billing and security issues.
Innovation Solution
A GTP filter is introduced to modify GTP parameters based on IMSI and APN data, ensuring correct routing of GTP messages to either the Dual/Multi IMSI platform or the MVNO's GGSN, bypassing the filter for other GTP control messages to maintain quality of service and avoid latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If automatic APN modification is enabled by the device based on IMSI, then the device can automatically configure GPRS parameters for the sponsor network, but the GTP traffic is wrongly routed to the sponsor network GGSN causing service failure
Solution Approach 1:
The patent introduces an intermediary mechanism (HLR/SGSN correction logic) that intercepts and corrects the automatically modified APN values before they are used for GTP routing. The HLR receives the automatically selected sponsor network APN, corrects it to the proper home network APN, and provides the corrected APN to the SGSN, thereby preventing wrong routing while maintaining automatic configuration behavior.
Solution Approach 2:
The patent applies preliminary action by correcting the APN value during the location update process before the actual data session establishment. The HLR performs the APN correction in advance based on the IMSI, so that when the device later establishes a data session, the already-corrected APN is used, preventing routing errors without requiring manual intervention.
2Productivity
If the HLR downloads sponsor network APNs during GPRS location update, then the GTP messages can be routed to the sponsor network GGSN, but real-time charging becomes complex requiring elaborate Diameter/GTP'/INAP/CAMEL based solutions
Solution Approach 1:
The patent extracts the APN correction function from the complex real-time charging system. Instead of using elaborate Diameter/GTP'/INAP/CAMEL-based charging solutions, the solution simply extracts and applies the correct APN value during the location update process, separating the routing correction function from the charging function and simplifying the overall system architecture.
3Ease of manufacture
If Dual/Multi IMSI roaming solution is used to enable faster implementation and ROI, then the mobile devices can piggyback on sponsor operator networks, but the automatic APN selection causes GPRS data services to fail
Solution Approach 1:
The patent uses the HLR as an intermediary that receives the automatically selected APN from devices using Dual/Multi IMSI roaming, corrects it to the appropriate home network APN, and provides the corrected value to the SGSN. This intermediary correction mechanism enables Dual/Multi IMSI roaming to work reliably with automatic APN selection, maintaining both fast implementation and service reliability.
Data Source
AI summary
In a method and system for APN (Access Point Name) correction in a GPRS data roaming scenario where a sponsor operator network is used and a method and system for routing GTP messages to the correct destination network entity after actuating the APN correction as and when required. The GTP filter checks the IMSI and APN data in the GTP layer and, depending on the IMSI and APN data performs APN correction and manipulates GTP parameters to ensure the PDP Context is correctly established between the SGSN and the GGSN, and the further GTP Control or Data messages bypass the GTP Filter application. This solution allows appropriate routing of message, in particular for message to and from smartphone.