<concept id="GUID-F4A99C9F-21E8-57BF-9DE7-EA6C091C22E5" xml:lang="en"><title>Telephony Server Plug-ins</title><shortdesc>Telephony server plug-ins translate modem messages into Symbian platform types. Symbian platform provides interfaces which must be implemented in the TSY for effective communication between the modem and Symbian platform. This section describes the telephony server plug-ins (TSYs). </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><p>Telephony applications use the client side API to access the functionality of the telephony server. The server translates the client request into the format used by the TSY modules. The TSY modules translate the client requests into hardware commands. The telephony server dynamically loads and unloads TSY modules at the request of clients. A basic TSY may support core telephony functionality, for example for making and terminating calls, on a wide range of hardware. A more advanced TSY may only support phone hardware from a specific manufacturer, or even just a single phone, for example a TSY supporting GSM functionality. </p> <p>To access extended functionality supported by specific telephony hardware, the following is required: </p> <ul><li id="GUID-A9860B1F-3B52-5637-9E40-CAD12FBEEE7B"><p>a standard extension of the client side API to make this functionality available to clients </p> </li> <li id="GUID-77D66187-CCB6-591C-B49D-94C0B717D6E9"><p>support for the functionality in a TSY module </p> </li> </ul> <p>When two manufacturers implement the same functions in different ways, different TSY modules are required. Both TSY modules respond to the same TSY API, but use different commands to control the telephony hardware. </p> </conbody></concept>