A. four station ports and four trunk ports （4xFXS and 4xFXO）
B. two station ports （2xFXS）
C. eight station ports （8xFXS）
D. one station port and one trunk port （1xFXS and 1xFXO）

A. reference to network ability to provide improved service to all network traffic
B. reduction in delay， jitter， and packet loss
C. equal handling of all packets
D. support for real-time applications
E. best-effort actions