VoLTE Roaming Interworking Function for Agreement-Free Voice and SMS
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Solution Overview
Problem
Existing VoLTE roaming technologies require pre-existing agreements between visiting and home operators, which is impractical for many network providers, preventing the shutdown of 2G/3G infrastructure and limiting voice and SMS services for inbound roamers.
Innovation Solution
An Interworking Function (IWF) that enables VoLTE roaming without such agreements by redirecting IMS traffic and providing CS-like services, including a Diameter Routing Agent, IMS Core, virtual HSS, and PGW to facilitate voice and SMS services for inbound roamers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VoLTE roaming is implemented without pre-existing agreements, then service coverage and accessibility are improved, but network security and control are worsened
Solution Approach 1:
The patent introduces an Interworking Function (IWF) as an intermediary component that sits between the visited network and the home network. This IWF acts as a mediator that enables VoLTE roaming without requiring pre-existing bilateral agreements between operators. The IWF handles the interworking between different network domains, providing the necessary mediation to allow service coverage expansion while maintaining network security through controlled interaction points.
2Productivity
If 2G/3G infrastructure is shut down to save frequency bands and reduce costs, then operational efficiency is improved, but service compatibility for inbound roamers is worsened
Solution Approach 1:
The patent implements a virtualization approach where virtual network functions (VNFs) are deployed to emulate the behavior of traditional 2G/3G network elements. Instead of maintaining physical 2G/3G infrastructure, the system creates virtual copies of these network functions that run on modern 4G/5G infrastructure. This allows the network to maintain service compatibility for inbound roamers while operating efficiently on shut-down or repurposed infrastructure.
Solution Approach 2:
The patent utilizes network slicing and dynamic parameter configuration to adapt the 4G/5G infrastructure to provide services traditionally associated with 2G/3G networks. By changing network parameters, slicing the network into different virtual instances, and dynamically configuring network behavior, the system can provide circuit-switched fallback and other legacy services over packet-switched infrastructure, maintaining service compatibility without physical legacy hardware.
3Reliability
If VoLTE roaming agreements are required between operators, then network control and quality of service are improved, but deployment complexity and time are worsened
Solution Approach 1:
The patent creates a universal IWF component that can serve multiple operators and network configurations without requiring operator-specific customizations. This multi-functional IWF can handle interworking for different home and visited network combinations, providing a standardized solution that reduces deployment complexity. The universal design allows the same infrastructure to serve multiple purposes and multiple operators, eliminating the need for bilateral agreements between each pair of operators.
Data Source
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AI summary
This invention is a system and method for implementing a VoLTE and circuit switched voice and SMS interworking function to provide voice and SMS service to roaming mobile devices at visiting network based on VoLTE roaming and 'SMS over SGs' towards VPLMN, and circuit-switched voice and SMS towards HPLMN. The interworking function enables and redirects IMS traffic at VPLMN towards a hosted IMS core with voice connectivity to PSTN via MGCF and MGW. The interworking function also performs circuit-switched location-update registration at HLR at HPLMN for receiving mobile-terminated voice calls and SMS.