high-speed Internet subscribers

Congress has asked Embarq Corp. about its work with a company that tracks online subscribers' Web traffic for advertising purposes, part of growing concern about Internet privacy.

Overland Park, Kan.-based Embarq is the nation's fourth-largest traditional telephone company with 1.34 million high-speed Internet subscribers in 14 states. It has been linked in the past with NebuAd Inc., a company that works with Internet service providers to tailor targeted ads based on what Web sites a particular subscriber visits.

Charter Communications on Wednesday abandoned plans to deploy NebuAd's user-tracking system after objections from Congress and privacy advocates. Its stock dropped slightly after the announcement.

The NebuAd system places tracking cookies and sells users' Internet data to advertisers for targeting ads. Charter had been testing the system that privacy watchdogs Free Press and Public Knowledge called a "classic man-in-the-middle attack."