Lawmakers promised Wednesday to put an end to shady practices by private data brokers who covertly gather Americans’ telephone records without subpoenas or warrants on behalf of banks, bail bondsmen and even federal and local police.

These brokers, many of whom market aggressively on the Internet, have tricked telephone carriers into revealing private customer information and broken into online accounts, sometimes by guessing passwords that were the names of pets, according to documents obtained by The Associated Press.