Telephony Integration and Conferencing
Telephony Integration and Conferencing |
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TAPI support is also built into clients running Microsoft® Windows® 95 and Microsoft® Windows® 98.
The telephony and conferencing infrastructure of Windows 2000 consists of the following elements:
Phone Dialer, which is a TAPI application, is included with Windows 2000. Phone Dialer can be used for basic telephony functions, as well as audio and video conferencing services.
The Phone Dialer makes TAPI function calls to utilize the Telephony Service Providers (TSPs), including the H.323 and the Multicast Conferencing Service Providers. In addition, the Phone Dialer can be used with TSPs supplied by other vendors.
To launch the Phone Dialer
Versions of the Microsoft Windows family of operating systems prior to Windows 2000 were supplied with TAPI 2.1 or earlier. (For instance, TAPI 1.4 was included with Windows 95 and can be upgraded to TAPI 2.1 through a free download; TAPI 2.1 was included with Windows 98.) These versions of TAPI provided a Microsoft® C-based procedural application programming interface (API).
Version 3.0 of TAPI is included with Windows 2000, but Windows 2000 continues to support previous versions of TAPI. TAPI 3.0 adds support for the Microsoft Component Object Model. A set of COM objects are provided to enable the use of any COM-compatible programming language, including Microsoft® Visual Basic®, Java, and Microsoft® Visual C++®, as well as scripting languages, such as Visual Basic® Scripting Edition (VBScript) or JavaScript, for writing telephony applications. The existing C API continues to be available under TAPI. Telephony applications written using the older version of C API are also still usable.
In addition to COM support, TAPI 3.0 also provides functionality for H.323-based IP telephony and IP multicast–based multiparty audio and video conferencing over TCP/IP data networks, by means of service providers included with the operating system.
A Telephony Service Provider (TSP) is a dynamic-link library (DLL) that supports communications to one or more specific hardware devices through a set of exported service functions. The service provider responds to telephony requests, sent to it by TAPI, by carrying out the low-level tasks necessary to communicate over the network. In this way, the service provider, in conjunction with TAPI, shields applications from the service-dependent and technology-dependent details of the network communication.
Developers write service providers to extend telephony services for existing hardware or to provide telephony services for new hardware. Each service provider supports at least one hardware device, such as a fax board, an ISDN card, a telephone, or a modem. The installation utility for a service provider associates that service provider with its hardware devices.
TAPI 3.0 supports two classes of service providers: telephony and media. Telephony Service Providers provide the implementation of signaling and connection control features, and Media Service Providers (MSPs) provide access to media content associated with those connections.
TSPs are mandatory service providers, and might optionally be associated with their own TSP-specific access to media content. MSP functionality is a new feature of TAPI 3.0, and is not supported on previous versions of TAPI.
Windows 2000 includes a set of service providers, which are described in greater detail later in this chapter. Windows 2000 Telephony Service Providers include:
Note
To install TSPs and MSPs from third-party vendors, follow the instructions they provide. To verify the installation, use the Telephony snap-in from the Start menu.