1. Essentials Guide
  2. Oracle USM Supporting the IMS Core
  3. HSS Server Assignment
  4. Entry Unregistration

Entry Unregistration

Because AoRs and not contacts are referenced by the HSS, an AoR is valid and should not be removed from HSS until all associated contacts have been removed or expired. If all the contacts are removed for an AoR by receiving REGISTER messages with Expires:0 header, then the SAR sent to the HSS includes Server-Assignment-Type of USER_DEREGISTRATION (5).

When the force-unregister option in the sip config is enabled, then the HSS is explicitly updated when all of the contacts for an AoR have expired. This event prompts the Oracle Communications Unified Session Manager to send a SAR to the HSS using the Server-Assignment-Type of TIMEOUT_DEREGISTRATION (4).

The HSS can send a Registration-Termination-Request to request removing a registration, which corresponds to entries in the Oracle Communications Unified Session Manager’s registration cache. When an RTR is received, the following AVPs are expected:

  • Private-User-Identity—Username of the user, which is being de-registered.
  • Associated-Identities—The Private-Id's in the same subscription which need to be de-registered. (optional)
  • Public-Identity—One or more public-Id's of the user being de-registered. (optional)

For the AoR specified by the Private-User-Identity AVP, all associated contacts are removed in the registration cache. The Oracle Communications Unified Session Manager sends a Registration Termination Answer to the HSS to indicate success.