MCI, Inc. was an American telecommunications company that was headquartered in Ashburn, Virginia. The corporation was the result of the merger of WorldCom (formerly known as LDDS followed by LDDS WorldCom) and MCI Communications, and used the name MCI WorldCom followed by WorldCom before taking its final name on April 14, 2003 as part of the corporation's emergence from bankruptcy.

For a time, WorldCom (WCOM) was the United States' second largest long distance phone company (AT&T was the largest). WorldCom grew largely by acquiring other telecommunications companies, most notably MCI Communications. It also owned the Tier 1 ISP UUNET, a major part of the Internet backbone. It was based in Clinton, Mississippi before moving to its present corporate headquarters.

Programming Labs Designed and programmed a system that linked into a mainframe in Greenville, SC, which allowed MCI to price the disparate user long distance rates using their own pricing structure. Developed a module that detailed duplicate POPS (Point-of-Present-Switches) between the two companies.

Designed a query tool that performed an analysis of all 56k, T1, T3 and local communication lines using variable pricing structures.