A case study: DX 200 Exchange
nSSU:
Subscriber Signaling Unit: controls access network
nCCSU:Common
Channel Signaling Unit (SS7).
nCCMU:
Common Channel Signaling Management Unit: (as MTP, SCCP)nPAU:
Primary Rate Access Unit: controls basic (64 kbit/s) system interfaces
n LSU: Line Signaling Unit: takes care
of signaling between transit exchanges and access networksnMFSU:
MULti-frequency Service Unit: Takes care of signaling when multiple frequency
signals are used