Roaming Call Routing with Selective Visited-Network Local Breakout
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Solution Overview
Problem
In IP Multimedia System (IMS) based roaming, there is no standardized way for Visited Public Land Mobile Networks (VPLMN) to intercept and route calls to special destination addresses such as emergency numbers and toll-free numbers to the visited network, requiring manual negotiations and commercial agreements between operators.
Innovation Solution
A method and system that utilizes a call management function to obtain a destination address, generate an inquiry to a data storage for special procedures, and send a control signal to the VPLMN core network to route calls accordingly, enabling Local BreakOut in the visited network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Home Routing model is used in IMS based roaming, then call routing is simplified to always route to home network, but VPLMN cannot intercept and route special number calls locally
Solution Approach 1:
The patent applies preliminary action by checking whether the destination address belongs to a special number category (emergency, toll-free, etc.) before executing the call routing. The call management function queries a data storage to determine if special handling is needed, and only then generates control signals to route via LBO. This pre-check mechanism enables selective local routing without complicating the overall Home Routing model.
2Manufacturing precision
If manual configuration is used for each special number routing, then routing precision can be achieved, but manual work and commercial negotiations are required
Solution Approach 1:
The patent implements self-service by enabling the visited network to autonomously determine routing decisions through automated queries to a data storage containing special number categories. The call management function automatically checks destination addresses against predefined categories (emergency numbers, toll-free numbers, etc.) and applies appropriate routing without requiring manual operator intervention or commercial negotiations for each number.
Solution Approach 2:
The patent applies universality by creating a standardized mechanism that handles multiple types of special numbers (emergency, pseudo-emergency, toll-free) through a single unified approach. The data storage contains universal category definitions that can be applied across different networks and countries, eliminating the need for network-specific manual configurations for each number type.
3Reliability
If LBO is used for emergency calls, then emergency call handling is standardized, but regular IMS calls cannot use LBO for special numbers
Solution Approach 1:
The patent applies local quality by differentiating routing handling based on the specific destination address category. Emergency calls (112, 911) continue to use standardized LBO procedures, while regular IMS calls to special numbers (toll-free, customer care) can selectively use LBO based on the call management function's determination. Each number category receives locally optimized handling appropriate to its specific requirements.
Data Source
AI summary
A method for managing a call originating from a roaming terminal device is provided, the method comprises: obtaining a destination address; generating an inquiry to data storage; receiving a response to the inquiry; and generating a control signal to a core network of a visited communication network (VPLMN) the terminal device is roaming, the control signal carrying data causing an instruction to the core network of the visited communication network (VPLMN) to route the call by the visited communication network (VPLMN) serving the roaming terminal device to the destination address. Also a call management function, a communication system and a computer program are disclosed.