ABSTRACT
CARRIERS SUCH AS AT&T CORP., MCI COMMUNICATION CORP., AND Sprint Corp. began offering virtual private networks (VPNs) in the mid1980s as a means to recapture revenue lost to private lines that carried voice and data between far-flung corporate locations. With private networks, corporations paid a flat monthly fee for leased lines, instead of per-minute usage charges. This meant that companies could put as much traffic on the lines as they wanted-through such techniques as multiplexing and compression-without paying long-distance carriers anything extra.
