ST. LOUIS, MO — The fourth-largest cable company in the U.S. has ditched a plan to monitor its customers’ internet use in order to determine their interests and sell the data to advertisers who want to target online pitches.Charter Communications said its data-collection efforts would have protected users’ personal information, but Charter customers and industry watchdogs labeled the plan profiling and likened it to illegal wiretapping.

“The fact is that it would have allowed profiling of an individual — where they were going and what they were doing online — and there was no guarantee that this information could not ultimately be compromised,” Rep. Edward J. Markey [D-MA], chairman of the House Energy and Commerce subcommittee on telecommunications and the internet, told the Washington Post. “They made the right decision in halting their test.”

Consumer tracking is a growing practice among American ISPs, and it concerns users and watchdogs alike because ISPs have access to every keystroke a customer makes. Invariably, companies that engage in “deep packet inspection” say the data collected is not personally identifiable and only is saved by reference number and not by name.

Charter was the largest ISP to announce a test plan to date. The company planned to begin the program in June in a small test market: Fort Worth, TX; Oxford, MA; Newton, CT, and San Luis Obispo, CA. However, on Tuesday Charter released a statement saying that even though “most broadband consumers would look upon this service favorably… some of our customers have presented questions about this service. As such, we are not moving forward with the pilots at this time.”

That is not to say the company won’t move forward with a similar plan in the future, according to Charter spokeswoman Anita Lamont. She told the Post the plan is hold “indefinitely,” but the company intends to “continue to look at these advertising services” as sources of potential revenue.

“It’s clear we need further education in Washington and elsewhere to address the concerns of privacy advocates,” Bob Dykes, chief executive of NebuAd, the company contracted to perform the monitoring for Charter, told the Post. The message that the technology protects privacy “hasn’t been understood by everyone.”

Deep packet inspection concerns privacy advocates because it gives snoops a much broader view of a consumer’s internet habits than is available through the use of cookies. On the Web, all data sent and received is divided into “packets,” which can be considered a sort of electronic envelope. Inside the packets are the contents of every Web page visited, every email sent or received, every search query entered and every instant message conversation. Most users have no idea their communications can be “read” by people they don’t intend to see the material.

According to the Post, at least 100,000 U.S. internet users routinely are tracked by deep packet inspection, and ISPs covering about 10 percent of U.S. subscribers either use the practice now or have tested it. A recent report by public interest groups Free Press and Public Knowledge identified five ISPs that are NebuAd clients: WOW, Embarq, Broadstripe, CenturyTel and Metro Provider.

Charter’s decision to abandon the test program came after to congressmen, Markey and Rep. Joe L. Barton (R-TX) sent a letter to the company suggesting the practice may violate U.S. law.

According to Jeff Chester, director of the Center for Digital Democracy, Charter clearly got the message. Its proposal “crossed a digital line in the sand that up till now hadn’t been challenged. Congress had accepted targeted internet marketing, but the fact that ISPs were going to do it clearly had the potential of creating a firestorm,” he told the Post.