1. Essentials Guide
  2. Oracle USM Supporting the IMS Core
  3. Limiting AOR Contacts

Limiting AOR Contacts

The Oracle Communications Unified Session Manager allows you to limit the number of contacts that apply to AORs. It also provides a configurable behavior allowing the system to either reject a new contact or overwrite an existing contact with the new one. The user specifies the maximum number of contacts and the operation mode on a per-registrar basis. Alternatively, the user can disable the feature. This feature is applicable to Cx and local database deployments.

The value for max-contacts-per-aor ranges from 0-256. A value of 0 disables the function. When max-contacts-per-aor is greater than zero, the Oracle Communications Unified Session Manager tracks the number of contacts registered per AOR. Settings for max-contacts-per-aor-mode include REJECT and OVERWRITE.

If you change the configured maximum while the system is operational, your setting only applies to new registrations. If there are more contacts than your newly configured maximum, the system removes older contacts. This ensures that the contacts are always within the configured maximum.

Both max-contacts-per-aor and max-contacts-per-aor-mode are RTC supported.

Maximum Contacts REJECT Mode

If the Oracle Communications Unified Session Manager receives a registration request that exceeds the maximum that you configured, it responds with a local response, a 403 Forbidden by default, and does not register the additional contact. The system only rejects registration requests that exceed the maximum. Existing contacts persist normally.

Maximum Contacts OVERWRITE Mode

If the number of contacts in the initial registration exceeds the maximum, the Oracle Communications Unified Session Manager selects only the highest priority contact based on q-values. If there are no q values, the Oracle Communications Unified Session Manager adds contacts in the order they appear in the REGISTER message until it reaches the maximum. The system then identifies the oldest contacts for overwriting using the last registered time stamp.

In all cases, the Oracle Communications Unified Session Manager follows this procedure to remove old contacts:

  1. If reg-id/instance-id is present in the contact, the system simply updates the contact.
  2. The system sends NOTIFY messages to the subscriber for whom the contact has been removed with a status of "terminated" and "de-activated" as the reason.
  3. The system removes the contact from the registration cache.