Specific Reason Headers in 503 Response

The Oracle Communications Session Border Controller issues a 503 Service Unavailable SIP response code when it fails to fulfill an apparently valid request because it is undergoing maintenance or is temporarily overloaded and so cannot process the request. This feature changes the reason phrase in the SIP response from the generic “Service Unavailable” to one that specifies the overload condition when exceeding provisioned session capacity, transcoding sessions, or DSP resources.

The Oracle Communications Session Border Controller sends SIP responses with the values of status-code and sip-reason in the local-response-map-entries configuration element as status text when the provisioned session capacity, transcoding sessions, or DSP resource capacity has reached its maximum limit and the capacity has been noted in the local-error parameter of the local-response-map-entries configuration element. The SBC issues the generic “Service Unavailable” when the capacity has not been noted in the in the local-response-map-entries configuration element. Additionally, this feature adds the values of q.850-cause and q.850-reason in the local-response-map-entries configuration element to the reason header when the value of add-reason header in the sip-config configuration element is enabled.

Specific Reason Headers in 503 Response Configuration

1. Access the entries configuration element.

   ORACLE# configure terminal
   ORACLE(configure)# session-router
   ORACLE(session-router)# local-response-map
   ORACLE(local-response-map)# local-response-map-entries
   ORACLE(local-response-map-entries)#

2. Select the entries object to edit.

   ORACLE(local-response-map-entries)# select
   
   
   
   ORACLE(local-response-map-entries)#

3. Type local-error followed by a space and then one of the following phrases:
   • licensed-session-capacity-reached — changes the sip-reason field in the SIP response from “Service Unavailable” to "SIP_LOCAL_ERROR_LICENSED_SESSION_CAPACITY_REACHED" when license session capacity has been reached.
   • transcoding-licensed-session-capacity-reached — changes the sip-reason field in the SIP response from “Service Unavailable” to "SIP_LOCAL_ERROR_TRANSCODING_LICENSED_SESSION_CAPACITY_REACHED" when there are no more available transcoding licenses.
   • dsp-resource-limit-reached — changes the sip-reason field in the SIP response from “Service Unavailable” to "SIP_LOCAL_ERROR_DSP_RESOURCE_LIMIT_REACHED" when there are no more available DSP resources.
4. Type done to save your configuration.