Dynamic IMRN Allocation for Circuit-Switched to IP Call Routing
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Solution Overview
Problem
In communication networks, there is a challenge in routing Session Initiation Protocol (SIP) calls from user equipment devices operating in circuit-switched domains to IP-only subscribers when packet-switched networks are unavailable or do not support Voice-over-IP, as these devices can only make E.164 number-based calls and not IP-based calls.
Innovation Solution
A system and method that involves an application server in the IP multimedia subsystem (IMS) network dynamically allocating an E.164 number from a pool of IP multimedia routing numbers (IMRNs) to map with the called party's SIP URI, allowing the SIP call to be routed through the IMS network infrastructure, and utilizing timers to ensure the validity of the allocated IMRN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a user equipment device in circuit-switched domain attempts to make a call to an IP-only subscriber, then the call can be initiated, but the call cannot be completed because the device can only make E.164 number-based calls while operating in circuit-switched domain
Solution Approach 1:
The patent introduces an IP multimedia routing number (IMRN) as an intermediary that bridges the circuit-switched and IP domains. The IMRN acts as a mediator that the circuit-switched device can dial (as it's an E.164 number) while simultaneously enabling routing to the IP-only subscriber through the IMS network infrastructure
Solution Approach 2:
The patent segments the call routing process into distinct phases: (1) allocation of IMRN by the application server, (2) transmission of IMRN to the user equipment via SIP messaging, (3) dialing of IMRN by the circuit-switched device, and (4) routing through IMS network to the IP subscriber. This segmentation allows each component to operate in its native domain
2Adaptability or versatility
If packet-switched networks are unavailable or do not support Voice-over-IP, then circuit-switched network can be used for call origination, but IP-based calls cannot be established
Solution Approach 1:
The patent applies local quality by making the user equipment device domain-agnostic while the network infrastructure provides domain-specific handling. The device simply dials the IMRN without needing to know whether it's calling an IP or circuit-switched subscriber, while the IMS network dynamically routes based on the called party's domain
3Adaptability or versatility
If E.164 numbers are dynamically allocated from a pool for mapping to SIP URIs, then call routing to IP subscribers is enabled, but the pool of available numbers may be depleted
Solution Approach 1:
The patent implements a number recycling mechanism where IMRNs are returned to the available pool after their associated calls terminate. The application server monitors call states and recovers used IMRNs for reuse, significantly extending the effective capacity of the IMRN pool beyond the static number of physical subscribers
Solution Approach 2:
The IMRN allocation system is dynamic rather than static. The application server dynamically allocates IMRNs based on real-time call需求和 pool availability, and dynamically recovers them when calls end. This dynamic management allows the system to adapt to varying traffic patterns and maximize resource utilization
Data Source
AI summary
Methods and apparatus for originating a Session Initiation Protocol (SIP) call from a user equipment (UE) device in a network environment including a circuit-switched (CS) network and an IP multimedia subsystem (IMS) network to a called party are disclosed. In one illustrative example, when the SIP call is originated by the UE device in the CS network domain, a SIP Invite message which includes a SIP Uniform Resource Indicator (URI) or Tel URI of the called party is sent from the UE device to the IMS network (e.g. to an application server (AS) node). At the AS node, a pool of E.164 numbers are maintained as IP multimedia routing numbers (IMRNs) which are utilized for mapping to or otherwise associating with called party URIs. Thus, the AS node dynamically allocates a select E.164 number with respect to the called party's URI received from the UE device, and returns it to the UE device in a SIP Response message, e.g., a SIP 380 (Alternative Service) message. Subsequently, the dynamically-allocated E.164 number is sent from the UE device in a call setup message for identification of the URI at the AS node, via the mapping, so that the SIP call may be properly routed towards the called party.