Study Says Cox, Comcast Internet Subscribers Blocked

Cox Communications appears to be interfering with file-sharing by its Internet subscribers in the same manner that has landed Comcast Corp. in hot water with regulators, according to research obtained by The Associated Press.

A study based on the participation of 8,175 Internet users around the world found conclusive signs of blocked file-sharing connections only at three Internet service providers: Comcast and Cox in the U.S. and StarHub in Singapore.

Of the 788 Comcast subscribers who participated in the study, 491, or 62 percent, had their connections blocked. At Cox, 82 out of 151 subscribers, or 54 percent, were blocked, according to Krishna Gummadi at the Max Planck Institute for Software Systems in Saarbruecken, Germany.

Philadelphia-based Comcast is the country's second-largest ISP, with 14.1 million subscribers. Atlanta-based Cox Communications is the fourth-largest, with 3.8 million. It is part of privately held Cox Enterprises Inc.

Comcast's practice of interfering with traffic was brought to light by user reports last year and confirmed by an AP investigation in October.

Consumer advocate groups and legal scholars criticized the interference, saying that letting an ISP selectively block some connections makes it a gatekeeper to the Internet. Their complaints prompted the Federal Communications Commission to launch an investigation, which is ongoing.

Legislation also has been introduced in Congress to guarantee "Net Neutrality," or equal treatment of traffic by Internet service providers.

Comcast maintained that the intervention was necessary to ensure that non-file-sharing traffic would not be impeded by a few heavy users of file-sharing programs like BitTorrent. But in February, it said it would stop selectively targeting file-sharing later this year.

Much of the FCC's attention to the matter has been focused on Comcast's secrecy -- before the AP's investigation, it acknowledged only in the most general terms that it was managing traffic.

At least since 2006, Cox's subscriber agreement has noted that the...