The TAPICLIENT_LineSetCallData function is called during a call to the lineSetCallData function.
LONG TAPICLIENT_LineSetCallData(
HMANAGEMENTCLIENT hmClient,
LPTAPIPERMANENTID lpPermanentID,
LPVOID lpCallData,
DWORD dwSize
);
lineSetCallData, TAPICLIENT_ClientInitialize, TAPIPERMANENTID