Global Call API for HMP on Windows Programming Guide — August 2006 35
Call State Models
3.2.2 Basic Call States at the Outbound Interface
The basic outbound call states are as follows:
Null state (GCST_NULL)
This state indicates that no call is assigned to the channel (time slot or line). This is the initial
state of a channel when it is first opened. This state is also reached when a call is released or
after the channel is reset. The channel in this state is available for making outbound calls.
Call Dialing (GCST_DIALING)
This state exists for an outgoing call when an outbound call request is made. The call signaling
or message is in the process of being prepared for transfer or being transferred across the
telephony network. In response, the remote side may request more information,acknowledge
the call, accept the call or answer the call.
Send More Information (GCST_SENDMOREINFO)
This state exists for an outgoing call when the user has received an acknowledgement of the
call establishment request that permits or requests the user to send additional call information
to the network in overlap mode. The information, typically digits, is in the process of being
prepared for transfer or being transferred across the telephony network (overlap sending or
partial dialing). (This state is optional and may not be supported in all technologies. See the
appropriate Global Call Technology Guide for information.) This state applies to E1, T1 and
ISDN technologies only.
Call Proceeding (GCST_PROCEEDING)
This state exists for an outgoing call when the user has received an acknowledgement that all
call information necessary to effect call establishment has been received and the call is
proceeding. The remote side can now accept or answer the call. (This state is optional and may
not be supported in all technologies. See the appropriate Global Call Technology Guide for
information.)
Call Alerting (GCST_ALERTING)
This state exists for an outgoing call when the calling user has received an indication that
remote user alerting has been initiated, typically ringing. The outbound call has been delivered
to the remote party, which has not yet answered the call.
Call Connected (GCST_CONNECTED)
This is a common state that exists for an outgoing call when the user has received an indication
that the remote user has answered the call. The calling and called parties are connected and the
call is therefore active on the related call channel.
3.2.3 Basic Call States for Call Termination
The basic call termination states are as follows:
Call Disconnected (GCST_DISCONNECTED)
This state indicates that the remote party has disconnected the call. The remote party can
disconnect the call prior to establishing a connection, that is, while the call setup is in progress.
Thus, the call does not have to be in the connected state before it can be disconnected. The user
must respond by dropping the call and releasing the internal resources allocated for the call.