Dynamic IMRN Pool for IMS Call Continuity
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Solution Overview
Problem
Current call continuity management in IMS networks faces challenges due to limitations in E.164 number length and reliance on Caller ID information, which can result in lost digits and disrupted call routing, especially during handovers between circuit-switched and IP-based networks.
Innovation Solution
The implementation of dynamically allocated IP multimedia routing numbers (IMRNs) that are mapped to unique user equipment (UE) device IDs, allowing for effective call continuity by maintaining a pool of E.164 numbers and using timers to ensure validity, thereby avoiding the need to append extra digits and ensuring reliable call routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If call reference identity digits are appended to the E.164 number to generate an IP multimedia routing number (IMRN), then call routing capability is improved, but the number length exceeds the 15-digit limitation specified under ITU-T standards, resulting in possible loss of extra digits during network routing
Solution Approach 1:
The patent segments the call routing function by separating the E.164 number (which remains within the 15-digit limit) from the call reference identity. Instead of appending digits to create a longer IMRN, the system uses the E.164 number as a routing key to look up the actual call reference identity in a database, thereby achieving call routing capability without exceeding number length limitations.
Solution Approach 2:
The patent introduces an intermediary mechanism - a database or lookup table - that maps E.164 numbers to call reference identities. The E.164 number acts as an intermediary key that enables indirect access to the full call reference information without requiring the full identity to be transmitted through the network, thus avoiding the digit loss problem while maintaining routing capability.
2Reliability
If reliance is placed on Caller ID information being provided to the CCCF element in the IMS network, then call continuity can be established, but this information may be lost in the international ISDN infrastructure using the ISDN User Part (ISUP) signaling
Solution Approach 1:
The patent applies preliminary action by pre-establishing the mapping between E.164 numbers and call reference identities in a database before the call actually needs to be routed. This ensures that when the call proceeds through the ISDN infrastructure, the routing information is already prepared and stored, eliminating the need to rely on Caller ID information that may be lost during transmission.
Solution Approach 2:
The patent extracts the critical routing information (call reference identity) from the Caller ID field and stores it separately in a database associated with the E.164 number. This separation allows the call routing to proceed using the robust E.164 number through ISDN infrastructure, while the extracted call reference identity is retrieved from storage, preventing information loss.
3Adaptability or versatility
If IMS is designed to support multiple registrations of a common Public Identity from different UE devices, then network flexibility is improved, but establishing correct call legs becomes paramount and more complex
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors and tracks which UE device is currently associated with which call reference identity. When multiple devices register with the same Public Identity, the system maintains feedback loops that track active calls and device states, enabling it to dynamically determine the correct call leg to establish based on current network state information.
Solution Approach 2:
The patent applies dynamics by making the call leg establishment process adaptive rather than static. The system dynamically determines which call leg to establish based on real-time information about which UE device is currently active or registered. The mapping between E.164 numbers and call reference identities is dynamically updated based on registration and deregistration events, allowing the system to handle multiple device registrations flexibly without excessive complexity.
Data Source
AI summary
In one embodiment, a scheme is disclosed for managing call continuity in a network environment including a circuit-switched (CS) network and an IP multimedia subsystem (IMS) network wherein unique identity (ID) information supplied by a user equipment (UE) device is utilized. A pool of dynamically allocable IP multimedia routing numbers (IMRNs) maintained at an IMS network node are used for associating an IMRN with call information received from the UE device, 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, the network node utilizes the IMRN mapping to effectuate call continuity with respect to the called party.