Dynamic IMRN Allocation for IMS Call Continuity
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Solution Overview
Problem
Current call routing processes in networks that integrate circuit-switched and IP multimedia subsystem (IMS) networks face issues with call continuity due to limitations in E.164 number length and reliance on Caller ID information, which can result in lost digits and disrupted call connections, especially during handovers between different network domains.
Innovation Solution
A method that utilizes unique identity information from user equipment devices, such as Instance ID and Globally Routable User Agent Uniform Resource Identifier (GRUU), to dynamically allocate IP multimedia routing numbers (IMRNs) within the IMS network, ensuring call continuity by maintaining a pool of E.164 numbers and employing timers to verify the validity of allocated IMRNs, and optionally quarantining them for future use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If E.164 number routing is used in CS-IMS networks, then call routing is enabled, but call continuity is disrupted during handovers due to number length limitations and lost digits
Solution Approach 1:
The patent introduces an IMS network node as an intermediary that maintains a mapping between E.164 numbers and IMRNs. During handover, this intermediary preserves the complete call identity information and reconstructs the routing number, preventing digit loss and ensuring call continuity across CS and IMS domains.
Solution Approach 2:
The patent segments the call routing process into distinct phases: initial call setup using E.164, handover detection, IMRN allocation, and call reconstruction. This segmentation allows each phase to handle specific requirements, with the IMRN mechanism specifically addressing the handover continuity problem without affecting other call processing functions.
2Reliability
If dynamic IMRN allocation is implemented, then call continuity is improved, but network node complexity increases due to mapping maintenance
Solution Approach 1:
The IMS network node performs multiple functions including call routing, IMRN allocation, mapping maintenance, and handover coordination. By consolidating these functions in a single multi-functional node, the patent avoids the need for separate dedicated systems for each function, thereby managing complexity while achieving call continuity.
Solution Approach 2:
The patent changes the routing parameter from static E.164 numbers to dynamic IMRNs during handover. The network node maintains a mapping table that translates between these parameters, allowing the system to switch between E.164-based routing in CS domain and IMRN-based routing in IMS domain, thereby managing complexity through parameter transformation rather than structural complexity.
3Reliability
If IMRNs are dynamically allocated for call continuity, then seamless handover is achieved, but resource utilization efficiency decreases due to timer-based validation and quarantine
Solution Approach 1:
The patent implements periodic timer-based validation of allocated IMRNs and quarantine mechanisms. While this ensures call continuity by validating active calls, it temporarily reduces resource utilization efficiency as IMRNs remain reserved during timer periods. The periodic nature of this validation balances reliability with eventual resource release for reuse.
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 (112) wherein unique identity (ID) information supplied by a user equipment (UE) device (302) is utilized. A pool of dynamically allocable IP multimedia routing numbers (IMRNs) maintained at an IMS network node (308) are used for associating an IMRN with call information received from the UE device (302), which can include at least one of a GRUU, Instance ID, and the called party number relating to a call. When the dynamically allocated IMRN is returned by the UE device (302), the network node (308) utilizes the IMRN mapping to effectuate call continuity with respect to the called party.