A private communications network intended for use by business customers with distributed operating centers. An ESN is actually a combination of the following:
switches and communication lines that make up the network
software that contains the dialing plan configuration that allows users at switch locations to communicate easily with users at other switch locations
Note: Network Alternate Route Selection (NARS) is the Meridian 1 or Succession 1000 software package that is actually used to configure an ESN network. The terms ESN and NARS are typically used in the marketplace to mean the same thing.