//accept incoming call by Holding "Active" call using "TAPI_CALL_ANSWER_HOLD_AND_ACCEPT".
res = tel_answer_call(__pTapiHandle, incomingCallHandle, TAPI_CALL_ANSWER_HOLD_AND_ACCEPT, &HandleCallbackResponse, this);
//accept incoming call by Holding "Active" call using "TAPI_CALL_ANSWER_HOLD_AND_ACCEPT".
res = tel_answer_call(__pTapiHandle, incomingCallHandle, TAPI_CALL_ANSWER_HOLD_AND_ACCEPT, &HandleCallbackResponse, this);