Which service uses telephone control messages and signals between the transfer points along the way to the called destination?
A. Signaling System 7 (SS7) B. Time-division Multiplexing (TDM) C. X.25 D. Frame relay Ans: A Signaling System 7 (SS7) uses telephone control messages and signals between the transfer points along the way to the called destination. Time-division Multiplexing (TDM) has information from multiple sources and allocates bandwidth on a single media. Circuit switching uses signaling to determine the call route, which is a dedicated path between the sender and the receiver. Basic telephone service and Integrated Services Digital Network (ISDN) use TDM circuits. X.25 and Frame Relay services have information contained in packets or frames to share non-dedicated bandwidth. X.25 avoids delays for call setup. Frame Relay uses permanent virtual circuits (PVCs).
