Lawmakers have ramped up their call for investigations on mobile carriers.
In a letter signed by 15 senators on Thursday, the group of lawmakers demanded investigations from the Federal Trade Commission and the Federal Communication Commission on wireless carriers selling location data to third parties.
That location data went to about 70 companies, without customers' consent, the Congress members said in the letter. The document is signed by senators including Ron Wyden, D-Oregon, Chuck Schumer, D-New York, Kamala Harris, D-California, Kirsten Gillibrand, D-New York, and Bernie Sanders, I-Vermont.
"It is clear that these wireless carriers have failed to regulate themselves or police the practices of their business partners, and have needlessly exposed American consumers to serious harm," the letter, addressed to FCC chairman Ajit Pai and FTC chairman Joseph Simons, said.
The FTC and the FCC did not respond to a request for comment.
The letter comes more than two weeks after a Motherboard investigation found that carriers like AT&T, Sprint, T-Mobile and Verizon were still providing customer location data — often for legitimate purposes like emergency services, but then handed over to shady buyers like bounty hunters.
The backlash caused T-Mobile, AT&T and Verizon to promise to completely end the practice by March, though many lawmakers remain skeptical. Sprint announced Jan. 16 that it was also ending the practice, though it does not state a deadline.
Senators are asking the FTC and FCC to investigate if wireless carriers and data aggregators knew that they were obtaining people's location data without their knowledge and consent. The lawmakers also request that mobile carriers be required to notify every single person whose location data was sold, and who bought that information.
The four major US carriers spent a combined $36.9 million on lobbying over privacy issues in 2018, according to government documents.
The letter on Thursday is the latest call for action on mobile carriers selling location data. Senators Wyden, Harris and Mark Warner, a Democrat from Virginia, called on the FCC to investigate the issue Jan. 9, while the House Energy and Commerce committee asked for an emergency briefing from the agency Jan. 11.
Republicans on that committee also demanded answers from all major carriers Jan. 16. Despite the mounting requests for answers, the FCC has not indicated that it is actively investigating mobile carriers.
Because federal agencies like the FCC are furloughed, chairman Pai declined the emergency briefing with Congress members over the issue. At the time, an FCC spokesperson said the agency was investigating wireless carriers selling location data, but paused over the government shutdown.
"Unfortunately, we were required to suspend that investigation earlier this month because of the lapse in funding, and pursuant to guidance from our expert attorneys, the career staff that is working on this issue are currently on furlough," the statement said.
The senators in the latest call for investigations are hoping for a response by Feb. 5.
"The wireless industry has repeatedly demonstrated a blatant disregard for its customers' privacy," the letter said. "It is therefore vital that regulators take swift action to ensure that consumers are protected."
This article originally appeared on CNET.