Metropolitan Fiber Systems Inc, later known as MFS Communications Company, was a last mile provider of business grade telecommunication products such as long distance, and Internet access through its own fiber rings in major central business districts throughout North America and Europe. MFS had three divisions; MFS Telecom: Access, MFS DataNet: X.25, Frame and ATM, and MFS Intelinet: Local and Long Distance voice. MFS purchased UUNET

UUNET

UUNET founded in 1987, was one of the largest Internet service providers and one of the nine Tier 1 networks. It was based in Northern Virginia and was the first commercial Internet service provider...

 in 1996 and was acquired by WorldCom soon after. With the newly acquired assets, WorldCom became a powerhouse in the late 1990s but fell into financial issues due to bad management from WorldCom executives. The majority of the Legacy MFS Executives (through the help of Kiewit

Kiewit

Kiewit is a parish and township within the northernmost section of the Dutch speaking Belgian municipality of Hasselt. It borders on the municipality of Zonhoven to the north and Genk to the east, with Kuringen, a part of Hasselt, to the west....

 and other investors) started another company, Level 3 Communications

Level 3 Communications

Level 3 Communications is a telecommunications and Internet service provider headquartered in Broomfield, Colorado.It operates a Tier 1 network. The company provides core transport, IP, voice, video and content delivery for most of the medium to large Internet carriers in North America and Europe...

.
MFS was well known as the first major CLEC bypassing ILEC connections and their high prices. It was one of the first CLECs.