SCSCF IMEI Verification During IMS Registration for Roaming Security
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Solution Overview
Problem
In existing 5G networks, International Mobile Equipment Identity (IMEI) checks are not consistently performed when a UE is roamed to a non-home network, potentially allowing illegitimate devices to access the network.
Innovation Solution
Implementing an Equipment Identity Register (EIR) check at the Serving Call Session Control Function (SCSCF) to verify the legitimacy of IMEI during IMS registration, with the SCSCF determining actions based on EIR response codes, including rejecting or continuing the registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IMEI check is performed only in home network, then network provider's control is improved, but security coverage deteriorates when UE roams to non-home network
Solution Approach 1:
The SCSCF is designed to perform dual functions: both IMS registration management and EIR checking. This allows the same network function to serve multiple purposes - managing voice/video calls while simultaneously verifying device legitimacy, eliminating the gap where roaming devices could bypass security checks.
Solution Approach 2:
The patent introduces an intermediary mechanism where the SCSCF acts as a mediator between the roaming UE and the EIR database. Even when the visiting network doesn't perform IMEI checks, the SCSCF intercepts registration requests, extracts IMEI information, queries the EIR database, and makes authorization decisions based on the response, thus bridging the security gap.
2Reliability
If EIR check is performed during IMS registration, then device legitimacy verification is improved, but registration process complexity increases
Solution Approach 1:
The patent merges the EIR checking process with the existing IMS registration workflow. The SCSCF extracts IMEI from the registration request message, performs EIR query, and processes the response within the same signaling flow, rather than creating a separate verification process. This integration minimizes additional complexity while ensuring security.
Solution Approach 2:
The SCSCF autonomously performs the EIR checking process without requiring external intervention or additional network functions. It automatically extracts IMEI from incoming registration requests, queries the EIR database, interprets response codes, and makes registration decisions based on pre-configured policies, making the system self-sufficient in device verification.
3Object-affected harmful factors
If SCSCF performs EIR check for all registration requests, then security coverage is improved, but processing overhead increases
Solution Approach 1:
The patent changes the operational parameters of the EIR checking process by implementing response code-based decision making. The SCSCF queries the EIR database and receives response codes that indicate device status (whitelisted, greylisted, blacklisted). Based on these parameterized responses and pre-configured policy thresholds, the SCSCF makes efficient registration decisions without requiring complex analysis of each device, thus reducing processing overhead while maintaining security.
Data Source
AI summary
The present teachings disclose a system and method for accessing a cellular network system including: checking, at a Serving Call Session Control Function (SCSCF), legitimacy of an International Mobile Equipment Identity (IMEI) included in an registration request with an Equipment Identity Register (EIR) check; determining a SCSCF action based on a response code of an EIR response from the EIR check; and performing the SCSCF action, wherein the registration request comprises an IP Multimedia Subsystem (IMS) REGISTER.