Avaya Definity TN777B Network Controller - R6 and earlier (Refurbished)Avaya Definity TN777B Network Controller (R6 and earlier). More Information Communicates control channel messages between the processor circuit pack and the distributed network of port circuit packs on the TDM bus Controls 4 data channels that process and route information directly from the processor circuit pack to customer connected equipment Has time of day clock with battery back for power failure or low voltage conditions Monitors the status of