Dynamic IMRN Allocation for CS to IMS Call Routing
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Solution Overview
Problem
Current call routing systems face issues when routing calls between circuit-switched (CS) and IP multimedia subsystem (IMS) networks, particularly due to length limitations in E.164 numbers and loss of Caller ID information in international ISDN infrastructure, leading to potential loss of call reference identity digits during handover.
Innovation Solution
A system and method that dynamically allocates IP multimedia routing numbers (IMRNs) from a pool maintained by the Call Continuity Control Function (CCCF) node, which are mapped to called party numbers, allowing for valid IMRNs to be used for call routing without appending extra digits, and includes timer mechanisms to ensure validity and optional quarantine for future use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If call reference identity digits are appended to E.164 number to generate IMRN, then call routing capability is improved, but number length exceeds 15-digit limitation causing digit loss
Solution Approach 1:
The patent segments the IMRN generation process by maintaining a pool of pre-allocated E.164 numbers that are dynamically assigned to serve as IMRNs. Instead of appending digits to create extended numbers, the system divides the routing function into: (1) a pool management component that maintains valid E.164 numbers, and (2) a dynamic allocation component that assigns these numbers as IMRNs. This segmentation allows the system to work within the 15-digit E.164 limitation while achieving IMRN functionality.
Solution Approach 2:
The patent introduces an intermediary pool of E.164 numbers that act as mediators between the calling party and the called party. Instead of directly using appended-digit IMRNs that exceed E.164 standards, the system uses this intermediary pool to: (1) receive the intermediary number from the calling party, (2) resolve it to the actual called party number, and (3) establish the call. This intermediary mechanism enables call routing without violating E.164 number length constraints.
2Loss of information
If Caller ID information is relied upon for call routing, then call identification is improved, but information is lost in international ISDN infrastructure
Solution Approach 1:
The patent extracts the call identification function from the Caller ID information that is vulnerable to loss in ISDN infrastructure. Instead of relying on Caller ID fields that may be dropped during international routing, the system extracts and uses the intermediary IMRN as the primary identification mechanism. The IMRN is embedded in the call setup signaling in a manner that ensures it is preserved throughout the routing process, separating the identification function from the problematic Caller ID information.
Solution Approach 2:
The patent performs preliminary action by pre-allocating and maintaining a pool of valid E.164 numbers that are designated as IMRNs before they are needed for call routing. This preliminary preparation ensures that when a call requires IMRN-based routing, a valid number is already available in the pool and can be immediately assigned and used. This advance preparation eliminates the need to generate or validate IMRNs during the call setup process, ensuring reliability without depending on Caller ID information that may be lost.
Data Source
AI summary
In one embodiment, a scheme is disclosed for managing call routing in a network environment including a circuit-switched (CS) network and an IP multimedia subsystem (IMS) network. When a call is originated by a user equipment (UE) device in the CS network, call information associated with the call is provided to a call continuity control function (CCCF) network node disposed in the IMS network. At the CCCF node, a pool of E.164 numbers are maintained as IP multimedia routing numbers (IMRNs) which are mapped to or otherwise associated with called party numbers. The CCCF node dynamically allocates a select IMRN with respect to a called party number received from the UE device and returns it to the UE device. The dynamically allocated IMRN is then utilized for routing the call towards the called party.