IMS Network Node IMRN Bridging for CS-Attached UE Calls
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Solution Overview
Problem
Current systems face challenges in managing Mobile-Terminated (MT) calls in networks that integrate Circuit-Switched (CS) and IP Multimedia Subsystem (IMS) domains, particularly in transferring active mid-call services and ensuring service continuity across these domains, which is not viable in the Release 7 timeframe, and there is a need for an architecture that allows IMS-based services to be implemented while maintaining control when the serving access network is in the CS domain.
Innovation Solution
The solution involves a method and system for managing MT calls by receiving a message indicating the call is to be delivered over a CS domain, storing call information, associating an IP Multimedia Routing Number (IMRN) with this information, transmitting alternative signaling messages to the UE device, and upon verifying the IMRN's validity, initiating an access leg and bridging it with the remote leg to establish an end-to-end path for the MT call between the calling party and the UE device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If IMS-based services are implemented in the IMS domain, then service functionality and versatility are improved, but device complexity and network architecture complexity increase when supporting CS-attached devices
Solution Approach 1:
The patent introduces an IP Multimedia Routing Number (IMRN) as an intermediary element that bridges the CS domain and IMS domain. The IMRN acts as a mediator that allows CS-attached devices to access IMS services without requiring direct integration between the two domains, thereby reducing network architecture complexity while maintaining service versatility
Solution Approach 2:
The patent segments the call delivery process into distinct phases: IMRN assignment in the IMS domain, alternative signaling transmission through the CS domain, and call setup completion. This segmentation allows each domain to operate independently with simplified functionality while achieving integrated service delivery
2Reliability
If Voice Call Continuity (VCC) is implemented to transfer calls between CS and IMS domains, then service continuity is improved, but device complexity and implementation difficulty increase in the Release 7 timeframe
Solution Approach 1:
The patent extracts the complex VCC functionality from the Release 7 timeframe constraints and replaces it with a simplified alternative signaling approach using IMRNs. This extraction allows service continuity to be achieved through a less complex mechanism that does not require full VCC implementation
Solution Approach 2:
The patent changes the signaling parameter approach by introducing IMRNs as a new parameter that simplifies the call transfer process between domains. Instead of implementing the complex VCC parameter set, the system uses IMRN-based alternative signaling that achieves the same service continuity goal with reduced complexity
3Ease of operation
If alternative signaling messages are transmitted to CS-attached devices, then ease of operation and service accessibility are improved, but information loss may occur during CS domain transmission
Solution Approach 1:
The patent creates a simplified copy of the IMS signaling information that is suitable for CS domain transmission. The alternative signaling messages contain essential call setup information in a format compatible with CS domain protocols, ensuring information integrity while maintaining ease of operation for CS-attached devices
Data Source
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AI summary
In one embodiment, a scheme is disclosed for managing delivery of a Mobile- Terminated (MT) call via an IMS network, wherein the MT call is originated by a calling party towards a User Equipment (UE) device that is CS-attached. An IMS-capable network node is operable to associate the received call information with an IP Multimedia Routing Number (IMRN) and provide the call information and the IMRN via alternative signaling (e.g., USSD or SMS messaging) to the UE device. A Mobile-Originated (MO) call process is initiated by the UE device using the received IMRN as the destination number, which terminates at the network node. Upon verifying that the returned IMRN is valid, the network node bridges the access and remote legs to establish the end-to-end path for the MT call between the UE device and the calling party.