AT&T is responsible for sending the most Internet traffic to businesses in the United States, according to a new report from comScore, highlighting data from September.

The report is an analysis of Internet Service Provider market share within businesses in the country. AT&T leads with 20% market share of all browser-based Internet page views.

Verizon came in second place with 12% share, followed by CenturyLink with 7%. The five largest business ISPs drove about 50% of business Internet traffic.

“The current state of the domestic business ISP market reveals a landscape led by a couple of top providers. However, even with smaller carriers contributing only a fraction of the traffic delivered by top carriers, the business ISP market is still more competitive than the residential ISP market,” said Greg Mishkin, comScore VP of Telecom and Wireless. “The small business segment is even more competitive among ISPs, highlighting the need for providers to develop strong marketing strategies to ensure they can retain and grow market share.”

Still, AT&T leads the pack across all sizes of business: large, small and medium-sized:

The top five ISPs account for nearly 70% of all traffic for large businesses. The percentage goes down, however, the smaller you go. The number is 56% for medium-sized businesses and 40% for small.