P-CSCF V-PLMN Identifier Verification in Roaming IMS
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Solution Overview
Problem
IMS entities in a home network face challenges in effectively acquiring the PLMN-ID of a visited network during roaming based on a home routed (HR) scheme, leading to inefficiencies in IMS registration and potential reliability issues due to discrepancies in PLMN-ID verification.
Innovation Solution
A method involving the P-CSCF generating a first V-PLMN identifier from the register message, transferring it to the HSS for verification against a second V-PLMN identifier acquired during the initial attach procedure, ensuring accurate PLMN-ID acquisition and verification using the S8 reference point for HR scheme determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the P-CSCF generates a V-PLMN identifier from the register message, then the IMS registration process can proceed, but the acquired PLMN-ID may be unreliable due to potential discrepancies with the actual visited network identifier
Solution Approach 1:
The HSS acquires the V-PLMN identifier during the initial attach procedure before the IMS registration process. This preliminary acquisition allows the HSS to have the correct visited network identifier ready for verification when the P-CSCF generates the identifier from the register message, ensuring reliability without delaying the registration process
Solution Approach 2:
The HSS verifies the V-PLMN identifier generated by the P-CSCF by comparing it with the pre-acquired identifier. This feedback mechanism ensures that any discrepancies between the generated and actual visited network identifiers are detected and can be handled appropriately, maintaining system reliability
2Reliability
If additional PLMN-ID change notification processes are implemented to ensure accuracy, then PLMN-ID verification reliability improves, but the complexity of network operations increases
Solution Approach 1:
The verification of the V-PLMN identifier is merged into the existing IMS registration process. The HSS performs the verification as part of its normal operations during registration, utilizing already-established signaling paths and procedures between the P-CSCF and HSS, thereby avoiding the need for separate complex notification processes
Solution Approach 2:
The HSS autonomously verifies the V-PLMN identifier by comparing it with its own stored information about the visited network. This self-service approach eliminates the need for additional network entities or complex inter-entity communication protocols to verify the PLMN-ID, simplifying overall network operations while maintaining high reliability
Data Source
AI summary
An embodiment of the present specification provides a method for acquiring an identifier of a visited public land mobile network (V-PLMN), in which a user equipment is roaming, by a proxy-call session control function (P-CSCF) of a home public land mobile network (H-PLMN). The method may comprise the steps of: receiving a register message from the user equipment; generating a first V-PLMN identifier on the basis of the register message; and transferring the first V-PLMN identifier to a home subscriber server (HSS), wherein whether the first V-PLMN identifier corresponds to an identifier of the V-PLMN which is serving the user equipment is verified by the HSS through comparison with a second V-PLMN identifier acquired in an initial attach procedure for an evolved packet core (EPC) of the user equipment.