: Handling failures of application servers that provide specific services (e.g., VoLTE, messaging). 3. Key Technical Mechanisms
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)
The specification has evolved through multiple "Releases" to keep pace with mobile technology: 123380
: Mechanisms for the Proxy-CSCF to recover its relationship with the user equipment (UE) after a restart.
: 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. : Handling failures of application servers that provide
: Procedures for recovering the Home Subscriber Server, which acts as the central database for user identities and profiles.
: Focused on basic IMS recovery for GSM and UMTS. ETSI TS 123 380 V9
: 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.