CSCF Roaming Logic for Selective SCG Call Routing
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Solution Overview
Problem
The Service Continuity Gateway (SCG) is unnecessarily involved in every call termination, leading to resource consumption, increased licensing costs, and call setup delays, even when not required, due to its inclusion in VoLTE and VoNR call flows, especially when subscribers are not roaming or not VoLTE capable.
Innovation Solution
The SCG is selectively invoked only when necessary, such as when a subscriber is roaming in a GSM network without a VoLTE roaming agreement, by determining the roaming status and IMS registration, thereby bypassing it in other cases to reduce traffic and licensing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SCG is included in every call termination path, then service continuity is ensured, but resource consumption increases and call setup delays occur
Solution Approach 1:
The patent extracts the SCG from the universal call termination path and retains it only where specifically needed. By determining roaming status and VoLTE capability, the system removes the SCG from non-roaming or VoLTE-capable subscriber paths, eliminating unnecessary involvement while preserving service continuity for those who require it.
Solution Approach 2:
The patent applies local quality by making the SCG involvement conditional rather than universal. Different treatment is applied based on local subscriber characteristics: roaming status, VoLTE capability, and network type. This ensures service continuity is maintained locally where needed without imposing SCG overhead globally.
2Reliability
If the SCG is included in every call termination, then service continuity is ensured, but licensing costs increase
Solution Approach 1:
The patent extracts unnecessary SCG invocations from the call flow by implementing conditional routing logic. By checking roaming status and VoLTE capability before SCG involvement, the system removes SCG from paths where it is not needed, directly reducing licensing cost while maintaining service continuity where required.
3Reliability
If the SCG is involved in every call termination, then call delivery is ensured, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by determining roaming status and VoLTE capability before initiating call termination through the SCG. This pre-assessment allows the system to avoid unnecessary SCG involvement, simplifying the call flow while ensuring call delivery is maintained for subscribers who require SCG services.
4Loss of energy
If the SCG is selectively invoked based on roaming status, then licensing costs are reduced, but system complexity increases
Solution Approach 1:
The patent uses preliminary action by assessing roaming status and VoLTE capability before SCG invocation. This pre-determination simplifies the overall system by avoiding unnecessary SCG involvement, reducing licensing costs while the added routing logic remains manageable through standardized decision criteria.
Data Source
AI summary
In some implementations, a call session control function (CSCF) may identify information associated with a user equipment (UE). The CSCF may determine, based on the information, whether the UE is roaming in a circuit switched mobility network. The CSCF may transmit signaling associated with delivering a call to the UE, wherein the signaling bypasses a service continuity gateway (SCG) on a call delivery path when the UE is not roaming in the circuit switched mobility network and the signaling traverses the SCG on the call delivery path when the UE is roaming in the circuit switched mobility network.