1. Essentials Guide
  2. ENUM Based Oracle Communications Unified Session Manager
  3. Oracle USM as Registrar
  4. Register Refresh

Register Refresh

When a UA sends a register refresh, the Oracle Communications Unified Session Manager first confirms that the authentication exists for that UA’s registration cache entry, and then is valid for the REGISTER refresh. Then, the lifetime timer (value in Expires: header) for that registration cache entry is checked.

If the timer has not exceeded half of its lifetime, only a 200 OK is sent back to the UA. If the timer has exceeded half of its lifetime, the Oracle USM sends a NAPTR update to the ENUM database.

This image depicts the OCUSM supporting a registration refresh via an ENUM server.

In addition to the baseline Oracle Communications Unified Session Manager REGISTER refresh conditions, an ENUM database update is required when one of the following conditions is satisfied:

  • The location update interval timer has expired—This value, configured in the sip registrar configuration element ensures that that ENUM database always has the latest user information by periodically sending Standard Queries.
  • The message’s call-id changes while the forward-reg-callid-change option in the sip config configuration element is set. This covers the case where the UA changes the Oracle Communications Unified Session Manager through which it attaches to the network.
  • The REGISTER message’s Cseq has skipped a number. This covers the case in which a user registered with Oracle Communications Unified Session Manager1, moves to Oracle Communications Unified Session Manager2, and then returns to Oracle Communications Unified Session Manager1.
  • The REGISTER message’s contact list has changed.

After receiving the entries from the ENUM database via the NAPTR query, the list is correlated with the internal registration cache. Appropriate DDNS updates are preformed (see: ENUM Database Correlation).

If the Oracle Communications Unified Session Manager updates the ENUM database due to one of the above conditions, the UA’s access-side Expires timer is reset to the REGISTER message’s Expires: header value, and returned in the 200 OK. This happens even in the case when the reREGISTER was received in the first half of the previous Expires period. In addition, the core-side location update interval timer is refreshed on both active and standby.

When the above four conditions are not met, the registration and reregistration expiration proceeds normally. If the access-side expiration timer has not exceeded half of its lifetime, only a 200 OK is sent back to the UA. If the timer has exceeded half of its lifetime, the Oracle Communications Unified Session Manager refreshes the registration to the ENUM server. Note: Upon a Call-id or contact list change, both the registration cache timer and the ENUM database are updated.