Challenger: Unisys

Unisys has 806 service agents in the U.S., and more than 1,700 in Asia and Latin America, according to Gartner. Unisys also provides on-site desktop services through 1,775 desktop technicians. The company supports over 1.1 million service desk users and handles over 7.3 million service desk contacts. It also supports over 1 million workplace device users and manages over 1.1 million physical desktops/notebooks and 4,500 virtualized desktops, according to Gartner.