This section describes the architectural relationships of the telephony API for applications.

The telephony API for applications provides access to the basic telephony functionality for applications. The telephony API for applications is a subset of the multimode telephony API that provides a rich set of telephony applications to the handset manufacturers.


The API is implemented as static linked library etel3rdparty.dll. The library must be linked in the client applications to access the telephony functions. The client applications access the functions with the CTelephony class.

Figure: Telephony API for Applications - Block Diagram


The CTelephony class provides a limited set of telephony functions to client applications. The CTelephony is built on top of the core, multimode and packet data telephony APIs. The CTelephony class provides client applications with the functions to :

  • dial a call

  • answer a call

  • get the capabilities of the line, the call and the network

  • get information about the basic and supplementary services of the network

The CTelephony class translates the client API request into the internal commands and forwards them to the telephony server. The telephony server forwards the command requests to the telephony server plug-in (TSY). The TSY is developed and customised by the handset manufacturers. The telephony functions available to client applications depend on the functions implemented in the TSY.

Platform security

The DLL for the telephony API for applications, etel3rdparty.dll is protected with the ALL -TCB capability. According to the Symbian Platform security model the client applications must have the minimum capability of ALL -TCB to use the DLL.