In telephony, desktop computers interact with telephony hardware. Most PBXs implement the computer-telephony integration (CTI) link by using hardware that connects the PBX to one or more computers. Communication between a PBX and computers is rarely straightforward, because many vendors implement the CTI link differently. Furthermore, there is no standard for encoding data on the CTI link. As a result, computer-based telephony programs often need to understand the switch's proprietary language, which requires a separate driver. By using TAPI, you can use one API that many programs can use to request telephony services, and supply one translator (called a telephony service provider) for each PBX or other piece of telephony hardware.

Windows supplies several telephony service providers. The telephony service provider that enables telephony client-server functionality is the Microsoft Windows Remote Service Provider. Proprietary hardware might require additional telephony service providers, which are normally packaged with the hardware or available from the equipment manufacturer.

Microsoft Windows client-server components

Windows includes the following components that support client-server CTI.

Server-side components

The following components are available on the telephony server:

  • Telephony snap-in. Enables administrators to administer and monitor a telephony server, lines, phones, and users.

  • Telephony service provider. Translates between the generalized commands created by the Telephony service and the proprietary commands that the hardware uses. Provided by the hardware vendor.

  • Telephony service. On the server side, communicates with the remote service provider running on the clients. Also communicates with telephony programs running on the server, such as the client manager program.

Client-side components

The following components must run on the client or appear on the client:

  • Telephony service. Communicates with client-side telephony programs by using the TAPI interface layer and acts as a link between those programs and the Windows Remote Service Provider.

  • Windows Remote Service Provider. Communicates over the network with the Telephony service running on the telephony server.

Note that these components do not include client-side TAPI-based programs. Some general purpose programs use TAPI. Specialized programs, such as those that manage call centers, are provided by independent software or hardware vendors.

Additional references