TapiCallState Enumeration

Member name	Value	Description
Unknown	0	The call exists, but its state is currently unknown.
Offering	1	The call is being offered to the station, signaling the arrival of a new call.
Dialing	2	The originator is dialing digits on the call.
Connected	3	The call has been established and the connection is made.
Disconnected	4	The call has been disconnected.
Idle	5	The call has been disconnected and is no longer active. This is the final state of the call before it's destroyed. A call can never transition out of the idle state.
Accepted	6	The call was in the offering state and has been accepted by the called party.
DialTone	7	The call is receiving a dial tone from the switch, which means that the switch is ready to receive a dialed number.
Proceeding	8	Dialing has completed and the call is proceeding through the switch or telephone network. This occurs after dialing is complete and before the call reaches the dialed party, as indicated by ringback, busy, or answer.
Ringback	9	The station to be called has been reached, and the destination's switch is generating a ring tone back to the originator. A ringback means that the destination address is being alerted to the call.
OnHold	10	The call is on hold by the switch. This frees the physical line, which allows another call to use the line.
OnHoldPendingConference	11	The call is currently on hold while it is being added to a conference.
OnHoldPendingTransfer	12	The call is currently on hold awaiting transfer to another number.
Conferenced	13	The call is a member of a conference call and is logically in the connected state.
SpecialInfo	14	The call is receiving a special information signal, which precedes a prerecorded announcement indicating why a call cannot be completed. AddTapi.NET will disconnected the call shortly and set the DisconnectMode property based on the special signal received.

Reference

Traysoft.AddTapi Namespace