Transmission systems : Introduction, Subscriber Loop Design, Unigauge Design for Telephone Customer Loop Plants Signal Multiplexing, Digital Transmission Systems, Optical Fiber Transmission Systems. Switching systems: Centralized Switching, Switching Techniques, Congestion in Space-Division Switching Networks, AND Time- Division Switching Networks, Nonblocking Networks. Modeling of traffic flows, service times and single-server queues: Distribution for Number of Arrivals in a Fixed Time Interval, The Interarrival Time Distribution, The Service Time Distribution, The Residual Service Time Distribution, The Birth and Death Process, Erlang Loss System and Erlang Delay System. Engset loss and delay systems. Local area networks. Polling networks. Token ring networks. Random access networks.