AT&T and Verizon may be facing new challenges from a host of new cable and CLEC competitors, but out of the incumbent telcos the pair continues to be the dominant duo in the Ethernet services market, according to Vertical Systems Group's latest U.S. Incumbent Carrier Ethernet Leaderboard. AT&T reported that strategic business services such as cloud, Ethernet and VPN grew 13.8 percent year-over-year and now account for 30 percent of wireline business revenues.