Abstract: The invention provides a telecommunications system exhibiting an architecture having a plurality of functional levels decoupled from one another by data transport systems. The communication facilities connected to the periphery of the system are terminated at the physical level only and the data is channelized for transmission through a channel switch to a first level of processing that provides channel services. The data is then multiplexed and transmitted to system and call processing resources via a frame transport system.

Abstract: A bus system for exchanging information between a plurality of circuits connected to the system. The bus system includes a polling bus, a message bus, and a bus controller. The bus controller polls each circuit to see if the circuits require access to the message bus. Information between the circuits is conveyed by first transmitting the information to the bus controller where it is temporarily stored. That information is then sent to the destination circuit by the bus controller. Information is thus conveyed over the message bus twice for every exchange of informaton between two circuits.