IMS Call Continuity via Dynamic Routable Number Allocation
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Solution Overview
Problem
Current call handover technologies face challenges in ensuring seamless voice-over-IP (VoIP) continuity when transitioning between IP-based packet-switched networks and circuit-switched cellular networks, as they lack efficient mechanisms for dynamically allocating routable numbers and managing call continuity across different domains.
Innovation Solution
The system employs Session Initiation Protocol (SIP) messaging to dynamically allocate routable numbers, such as IP multimedia routing numbers (IMRNs) or Voice Call Continuity (VCC) Domain Transfer Numbers, which are uniquely identified and managed within the IMS network, allowing for seamless call continuity by providing a routable number that can be used across different radio access technologies and domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current call handover technologies are used to transition between IP-based packet-switched networks and circuit-switched cellular networks, then call continuity can be maintained, but the system lacks efficient mechanisms for dynamically allocating routable numbers and managing call continuity across different domains
Solution Approach 1:
The patent introduces an intermediary mechanism using SIP messaging and a central server to mediate between different network domains (IMS and CS networks). The server dynamically allocates routable numbers (IMRNs) and manages the handover process, acting as a mediator that coordinates call continuity without requiring complex direct integration between all network components.
Solution Approach 2:
The system implements dynamic allocation of routable numbers through SIP messaging. The server dynamically assigns IMRNs from a pool based on available resources and network conditions, allowing the system to adapt to varying call loads and network states. This dynamic approach replaces static routing configurations with flexible, on-demand number assignment.
2Reliability
If dynamically allocated routable numbers are used for call continuity, then seamless VoIP call transfer between domains is enabled, but the system requires sophisticated SIP messaging and number management mechanisms
Solution Approach 1:
The SIP messaging protocol provides built-in feedback mechanisms where the server responds to client requests with SIP response messages containing allocated IMRNs. The system uses feedback loops to verify call setup success, handle failures, and manage the lifecycle of allocated numbers, ensuring reliable call continuity while automating the management complexity.
Solution Approach 2:
The system manages call continuity by changing key parameters such as routing numbers, domain identifiers, and network addresses during handover. The server dynamically modifies these parameters in SIP messages to transition calls between IMS and CS domains, transforming static routing parameters into dynamic, adaptable values that ensure continuous service.
3Adaptability or versatility
If a pool of E.164 numbers is maintained as IP multimedia routing numbers for dynamic allocation, then call continuity can be managed across multiple domains, but the system requires sophisticated number pooling and allocation algorithms
Solution Approach 1:
The system maintains a pre-configured pool of E.164 numbers ready for allocation before calls need to be routed. This preliminary preparation of available numbers allows the server to quickly assign IMRNs without delay during call handover, improving allocation efficiency. The pool is maintained in advance with numbers pre-formatted and ready for immediate deployment.
Solution Approach 2:
The SIP-based number allocation system operates autonomously, with the server automatically assigning numbers from the pool based on incoming call requests without requiring manual intervention. The system self-manages the allocation process, tracking assigned numbers and returning them to the pool when calls complete, thereby improving allocation efficiency through automated operations.
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
In one embodiment, a scheme is disclosed for managing call continuity in a network environment (100) including a circuit-switched (CS) network and an IP multimedia subsystem (IMS) network (350) wherein a SIP Invite message having a Domain Transfer-URI contained in the Request-URI that is operable to trigger a return of a routable number is utilized. Responsive to the SIP Invite message from a UE device (302), a network node (308) provides a SIP response message (e.g., SIP Alternative Service 380 Response) which includes one or more radio access technologies and an alternative domain available to the UE device (302) for continuing a call from one domain to another domain.