Answer supervision reporting is an enhancement to the information request (IRR) Registration, Admission, and Status (RAS) protocol message that enables gatekeepers to maintain call accounting information by reporting the call connection time of connected calls to the gatekeeper.
In H.323 configurations, the endpoint (gateway) uses direct call-routed signaling. Gatekeepers do not have real-time knowledge or control over the state of a call and are dependent on the endpoints to provide them with necessary real-time information, such as call connect time, call termination time, and call termination reason.
When a call ends, the gateway sends a DRQ message with the BillingInformationToken (which contains the duration of the call) to the gatekeeper. If for some reason the gatekeeper does not receive the DRQ message, the gatekeeper does not have the information about when the call started or the duration of the call, which is necessary to maintain accounting information.
Answer supervision reporting allows the call connection time to be reported to the gatekeeper upon the connection of a call and at periodic intervals thereafter. Answer supervision reporting adds a proprietary Cisco parameter, the call connection time, to the perCallInfo parameter in the nonStandardData field, which is located in the IRR message. When a connect message is received, the originating gateway sends the unsolicited IRR message to its gatekeeper. On sending a connect message, the terminating gateway sends the unsolicited IRR message to its gatekeeper. If the ACF message has a nonzero value for the IRR frequency parameter, the gateway sends the unsolicited IRR message to its gatekeeper at periodic intervals, which are determined by the value in the IRRfrequency parameter.
With the exception of containing the call connection time in the perCallInfo parameter, the IRR message and its functionality remain the same.