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Call Control
The developer's view of telephony is one in which telephone lines and phone
sets are logically connected through TAPI. This logical connection also provides
a point of termination for the telephone line. The physical connection can be
made at the desktop, or at a LAN-based host or server, where a LAN protocol extends the connection of the phone lines or phone to the client application. TAPI
uses a first-party call-control model on the logically terminated line as well as
control of the associated phone device, if any.
Applications access Telephony API services using a first-party call control
model. This means that the application controls telephone calls as if it is an
endpoint (the initiator or the recipient) of the call. The application can make
calls, be notified about inbound calls, answer inbound calls, invoke switch
features such as hold, transfer, conference, pickup, and park, and can detect and
generate DTMF tones for signaling remote equipment. An application can also use
TAPI functions to monitor call-related activities occurring in the system.
In contrast, third-party call control means that the controlling application
does not act as an endpoint of the call. A third-party call-control model allows
an application to establish or answer a call between any two parties the application does not act as either of these parties.
A service provider may implement TAPI's line and phone functions by treating
the set of all stations on the switch as a single line device to which multiple
phone numbers are assigned. Each phone number on the line device maps to one of
the stations on the switchthat is, calls passing through the switch can reach a local station by using
its address (telephone number). The application can answer calls or make calls,
selecting any one of the addresses on the line device as the origination
number. Although the application appears to be the originating party, a call is
actually established between the station whose address was selected by its
originating number and the other party. However, this implementation is a type of
third-party call control and is not a design goal of TAPI, which emphasizes
first-party call control applications.
Related Links
Software for Delphi and C++ Builder developers
Software for Visual Studio .NET developers
Software for Visual Basic 6 developers
Delphi Tips&Tricks
MegaDetailed.NET
More Online Helps
Win32 Programmer's Reference (win32.hlp)
Win32 Multimedia Programmer's Reference (mmedia.hlp)
OLE Programmer's Reference (ole.hlp)
Microsoft Windows Pen API Programmer's Reference (penapi.hlp)
Microsoft Windows Sockets 2 Reference (sock2.hlp)
Unix Manual Pages
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