Switched Services—Local and Long Distance Calling

Telecommunications is booming. Users in North America are quickly gobbling up new telephone numbers. Consider the rate at which new area codes are used up. The original 144 area codes lasted from 1947 to 1995. From 1995 to 1999, 131 new area codes were assigned. Much of this appetite for telecommunications services is taking place on the public switched telephone network.

The public switched telephone network is analogous to a network of major highways originally built by a single organization but added to and expanded by multiple other organizations. Traffic enters and exits these highways (long distance lines) from multiple "ramps" built by still more organizations (e.g., the local telephone companies and competitive access providers).