WASHINGTON – Even as others cited the Fifth Amendment, a former data broker enthralled Congress yesterday with a bizarre, behind-the-scenes lesson on how this shadowy industry covertly gathers Americans’ telephone records without subpoenas or warrants.

Some lawmakers gasped and others shook their heads in amazement during testimony from a former data broker run out of the business years ago by Colorado police, James Rapp.

Others identified as active data brokers refused to answer questions about how they conduct business, invoking their constitutional rights against saying anything that might be used by prosecutors.

Mr. Rapp described what steps he would use, for example, to locate and steal the credit-card records of Rep. Jan Schakowsky, a Democrat of Illinois, saying he would first trick a utility operator to disclose her home address. He also boasted that he could uncover the bank password of Rep. Jay Inslee, a Democrat of Washington, in one hour.

“It’s just playing the game,” said Mr. Rapp, who told lawmakers he now cares full-time for his elderly mother in Colorado and lives off his family’s savings.

Lawmakers were impressed – and troubled – as Mr. Rapp explained how easily customer service representatives at America’s leading telephone and credit companies can be duped into disclosing private account information.

“I don’t think we have any privacy at all,” Rep. Cliff Stearns, a Republican of Florida, said.

Brokers have tricked telephone carriers into disclosing private customer information and broken into online accounts, in some cases guessing passwords that were the names of pets, according to documents obtained by the Associated Press.

“She has two pets, one named Rainbow and the other is Max,” Donnie Tidmore of Waco, Texas, wrote in September in an e-mail to one such data broker, PDJ Investigations of Granbury,Texas.

Mr. Tidmore, a private detective, also works as police chief in nearby Crawford, Texas, where President Bush owns his ranch. Mr. Tidmore wanted lists of cellular calls and the Social Security number of a Virgin Mobile USA subscriber for a case.

Mr. Tidmore told the AP yesterday that the data brokers he used obtained information through legal means, but he acknowledged he has no idea how PDJ could obtain another person’s phone records lawfully without a subpoena or warrant.

Mr. Tidmore said that, in his capacity as police chief, he would have needed a subpoena or warrant to obtain a citizen’s phone records.

PDJ’s owner, Patrick Baird, was among 11 people identified as data brokers who refused to testify during yesterday’s congressional hearing, invoking their Fifth Amendment rights not to incriminate themselves. They included Jim Welker, a Colorado state lawmaker who operated Universal Communications Co., which advertised it could obtain lists of anyone’s telephone calls for $50.

The head of the House Energy and Commerce Committee, Rep. Joe Barton, a Republican of Texas, promised to press for a broader vote in Congress soon on legislation the panel already approved to outlaw efforts to impersonate customers to trick companies into disclosing personal records, a practice known as “pretexting.”

Another data broker, Michele Yontef, smiled slightly when Rep. Ed Whitfield, a Republican of Kentucky, read excerpts from an e-mail she sent to a colleague in July 2005 in which she complained: “I was shot down four times. … I keep getting northwestern call center and they just must have had an operator meeting about pretext as every operator is cued in.”

Ms. Yontef was described as legendary among data-brokers, so skillful in obtaining private phone records that she was known as “Ma Bell.” She also declined to answer questions from lawmakers, citing the Fifth Amendment.

The congressional inquiry was expected to resume today, when lawmakers question officials from federal and local police agencies over their use of data brokers to gather personal telephone records without a subpoena or warrant.