Silent monitoring in a voice-over-data-network environment

A system and method for silent Automatic Call Distributor (ACD) call monitoring in a telephony over LAN environment includes an ACD agent terminal (10) for handling incoming calls from customers. A first call (15) between the agent terminal and a customer terminal (14) includes agent voice data (16) and customer voice data (18). After the agent terminal has set up (46 and 64) the first call with the customer terminal, the agent terminal receives (48 and 66) a monitoring call setup request (22) from a supervisor terminal (12). In response to the call setup request, the agent terminal cooperates with the supervisor terminal to establish (50 and 68) a monitoring call over which the agent terminal transmits the agent voice data and the customer voice data to the supervisor terminal. The agent terminal monitors (56 and 76) the first call for simultaneously transmitted agent voice data and customer voice data. In order to minimize transmission delay in the monitoring call, the agent and customer voice data which was simultaneously transmitted in the first call is reformatted for transmission in the monitoring call. In a preferred embodiment, agent voice data bytes are multiplexed (60) with customer voice data bytes in a consecutively sequential manner and the resulting combination voice data packets are transmitted (62) over the monitoring call. In a second embodiment, the framing of voice data packets in the customer and agent voice data streams is shifted (80) prior to alternately transmitting (82) customer and agent voice data packets over the monitoring call.