Charter has told its high-speed Internet customers in four markets about the pilot, which will produce enough information for Web advertisers to target online advertising for individual customers based on their habits.

The ads "will better reflect the interests you express through your Web-surfing activity," Charter senior vice president Joe Stackhouse told the affected subscribers in a letter. "You will not see more ads — just ads that are more relevant to you."

In response to the announcement, Rep. Edward Markey (D-Mass.) and Rep. Joe Barton (R-Texas) asked Charter President and Chief Executive Neil Smit to put the plan on hold until the three can confer.

The tracking is set to begin in June in Ft. Worth, Texas; San Luis Obispo, Calif.; Oxford, Mass.; and Newtown, Conn.

Subscribers can opt out of the tracking, though they must provide their name and address to install an opt-out cookie on their computer.

Should Charter instead offer subscribers the ability to opt in if they want to participate?