VSG: Lumen, AT&T, Spectrum Enterprise Are Again Top Carrier Ethernet Providers Posted on Share Home » VSG: Lumen, AT&T, Spectrum Enterprise Are Again Top Carrier Ethernet Providers Lumen (CenturyLink), AT&T and Spectrum Enterprise, in that order, retained their positions as the top carrier Ethernet providers on Vertical Systems Group’s 2020 Carrier Ethernet Leaderboard. Vertical Systems Group (VSG) says that overall port growth was flat due to the COVID-19 pandemic. There were four other providers on the leaderboard, which is based on attaining at least 4% of the U.S. retail Ethernet market. They were Verizon, Comcast, Windstream and Cox.