An agent workstation in a computer-telephony system is controlled to provide a fault tolerance technique. A telephony device driver in the workstation is controlled by a server process in the workstation. A first client process interfaces a controller to the server process. The controller is also interfaced to the server process by a second client process, the second client process serving as an alternate interface between the controller and the server process in the event of failure by the first client process. Control of the server process by the controller is transferred from the first client process to the second client process in the event of failure by the first client process.