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: Procedures for recovering the Home Subscriber Server, which acts as the central database for user identities and profiles.

: Handling failures of application servers that provide specific services (e.g., VoLTE, messaging). 3. Key Technical Mechanisms 123380

: Integrated support for LTE and 5G networks, ensuring that high-speed packet-based services remain resilient. Summary Table: Typical Restoration Nodes Role in Restoration Primary Data Stored S-CSCF Serving node; handles session control SIP proxies, Contact info, Auth info HSS Central database; restores S-CSCF data Private User Identity, Registration Sets P-CSCF Entry point; detects UE status UE local IP, Security associations : Procedures for recovering the Home Subscriber Server,

: Nodes use indicators (often via IETF RFC 6223) to detect the availability of peers and trigger restoration if a failure is detected. 4. Evolution and Versions Key Technical Mechanisms : Integrated support for LTE

: Procedures for when a Serving-Call Session Control Function (S-CSCF) fails or loses registration data. It defines how the Home Subscriber Server (HSS) and other nodes collaborate to re-register users or restore sessions.

The primary goal of TS 23.380 is to ensure service continuity and high availability within the IMS core network. While network nodes (like the S-CSCF, HSS, and P-CSCF) are designed for reliability, maintenance or unforeseen failures can cause data loss or corruption. This document standardizes automatic restoration procedures to minimize user impact when these events occur. 2. Core Restoration Scenarios