123380 May 2026

: 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

The specification covers several critical failure and recovery scenarios across the IMS domain:

For further technical reading, the latest versions (such as ) are available via the ETSI Deliverable Repository . ETSI TS 123 380 V9.6.0 (2014-03) 123380

The specification has evolved through multiple "Releases" to keep pace with mobile technology:

Restoration relies on specific signaling flows and data synchronization methods: : Nodes use indicators (often via IETF RFC

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

: During initial registration, the S-CSCF backs up critical data—such as the list of SIP proxies, contact information, and authentication schemes—to the HSS. ETSI TS 123 380 V9

: Mechanisms for the Proxy-CSCF to recover its relationship with the user equipment (UE) after a restart.