# Monitoring the proceeding call state

When the switch has accepted the call set up request, and is in the process of ringing the receiving end, the application receives NCCEVN_CALL_PROCEEDING. Call progress analysis is begun. The call state changes to proceeding.

If the call meets other connection criteria specified in this mask, the application receives NCCEVN_CALL_CONNECTED, and the call enters the connected call state. If the call does not meet the connection criteria or meets the disconnectmask criteria, the application receives NCCEVN_CALL_DISCONNECTED, and the call proceeds to the disconnected call state. In either case, the event's value field contains the reason for connection or disconnection.

The application can receive NCCEVN_BILLING_INDICATION while in the proceeding call state. This event indicates that a billing indication arrived. Depending upon the protocol, this indication may be a billing pulse or some more complex indication such as ISDN or SS7. In some cases, the value field of this event contains the billing units charged. No state transition occurs with this event. The application can invoke nccQueryCapability to determine if the protocol supports billing indications.

The NCC.START.eventmask parameter controls whether two other events appear during the proceeding call state:

Event | Description
NCCEVN_REMOTE_ALERTING | Indicates that the remote end is ringing. Does not cause a state transition. NCCEVN_REMOTE_ALERTING is generated only if the NCC_REPORT_ALERTING bit is set in the NCC.START.eventmask parameter.
NCCEVN_REMOTE_ANSWERED | Generated at the first positive indication that the remote party has answered. For example, out-of-band signaling, voice, or modem tone. The event value field contains the indication type. No state transition occurs. NCCEVN_REMOTE_ANSWERED is generated only if the NCC_REPORT_ANSWERED bit is set.

For more information, see NCC API global parameters.