The Avaya TN777 Network Controller Card communicates control channel messages between the processor circuit pack and the distributed network of port circuit packs on the TDM bus.
It also controls 4 data channels that process and route information directly from the processor circuit pack to customer connected equipment.
It has a time of day clock with battery backup for power failure or low voltage conditions. The TN777 monitors the status of the system clocks and alerts the processor circuit pack in the event of a failure of any clock.
The TN777 also supports ISDN.