A Tennessee company will stop selling personal cell phone records of individuals over the Internet and will provide information on how it acquired such data under an agreement reached last week with Verizon Wireless.

The firm, Source Resources Inc. of Cookeville, Tenn., was among dozens of companies advertising that for fees starting under $100, they would provide records of calls placed to and from any phone user.

Call records frequently are used by law enforcement, which obtains them through court orders. But small data brokers and private investigators have made a business of getting and selling the information online, often acquiring the information using deceptive or illegal practices, according to experts.

Although phone records cannot lead to the type of financial fraud that can result when other types of personal data are stolen, experts said they can be exploited by criminals, such as stalkers or abusive spouses trying to locate their victims.

Wireless carriers say cases of purloined records are rare and that they take measures to safeguard the information. But the Electronic Privacy Information Center, a leading privacy rights group, last month urged the Federal Communications Commission to crack down on carriers for having inadequate security.

Verizon Wireless sued Source Resources in July, after a Verizon Wireless customer complained that his records had been obtained from Source Resources without his permission.

Officials at Source Resources did not return messages seeking comment.

Verizon Wireless spokesman Jeffrey Nelson said that the information was obtained through a commonly used tactic known as pretexting.

The companies that sell the records impersonate actual customers, using private data provided by the people seeking to buy the information. Nelson said the company is continually updating its procedures and training of call-center employees to guard against pretexting.

And he said Verizon Wireless is looking forward to learning more about the various sources of call records and how they are acquired.

"If you are one of these companies that are stealing people's identities, you better sleep with one eye open," Nelson said.