The application is notified of errors encountered in processing transaction requests by the TCAP layer at any time with unsolicited TCAP status indication messages (event type TCAP_EVENT_STA_IND). The status field returned in the status indication message indicates the reason for the error.
Transaction requests that could not be delivered by the SCCP layer due to routing errors, global title translation failures, or temporary network outages, for example, are returned to the originating application if requested through the SCCP quality of service parameters with unsolicited TCAP notify indication messages (event type TCAP_EVENT_NOT_IND). The notify indication includes a return cause field that identifies the reason the message could not be delivered.