NEW YORK - Although a large Internet service provider has backed away from technology that tracks subscribers' Web use in order to deliver personalized advertising, two other broadband companies said Wednesday they are still considering whether to deploy it.

Phone companies Embarq Corp. and CenturyTel Inc. have both completed trials of the same tracking system, from online advertising company NebuAd Inc., and are now considering whether to proceed.

The largest U.S. Internet provider that had been actively looking at Web tracking, Charter Communications Inc., announced Tuesday that it had canceled its planned test because customers had raised concerns.

The technology gathers data on the interests of Web surfers by looking at the sites they visit. It passes the information to online advertising companies, without revealing a surfer's identity, so they can display more relevant ads on Web sites. For instance, a surfer who visits sites about dogs might see more banner ads for dog food.

The system has been criticized by privacy advocates and legislators. Rep. Edward Markey, D-Mass., and Rep. Joe Barton, R-Texas, wrote to Charter asking it to put the test on hold to give time for discussions. Markey chairs the House Subcommittee on Telecommunications and the Internet.

"We are not currently using behavioral targeting tools and have not decided whether to move forward with them, either through NebuAd or with any other vendor," said Debra Peterson, spokeswoman at Embarq.

The Overland Park, Kan., company is the country's ninth-largest ISP, with 1.34 million broadband lines at the end of March.

Tony Davis, the head of investor relations at CenturyTel, said it was his understanding that the reaction to Charter's proposed test had to do with cable-industry regulations that don't apply to a phone company.

"So at this point it's not affecting our thinking," Davis said.

Monroe, La.-based CenturyTel had 586,000 broadband customers at the end of the first quarter.