AT&T and T-Mobile US vowed to fight hefty fines proposed as a punishment by the Federal Communications Commission (FCC) for selling customer location data, disputing accusations they failed to adequately protect user privacy.

Jim Cicconi, AT&T senior EVP of External and Legislative Affairs, told Mobile World Live (MWL) the operator screened providers of location-based services, limited their use of information and never shared the data without first obtaining verification of customer consent.

He added AT&T “immediately shut down their access to this data” when reports surfaced suggesting unauthorised uses had occurred.

“We aggressively protected customer information in full compliance with FCC rules,” Cicconi said, adding the operator will “vigorously contest” the proposed fines and “demonstrate that we acted appropriately and lawfully at all times”.

A T-Mobile representative told MWL it also plans to fight the proposed punishment, arguing it was the first operator to commit to ending its location data sharing programme, acting in February 2019 “after first ensuring that valid and important services were not adversely impacted.

“We take the privacy and security of our customers’ data very seriously…While we strongly support the FCC’s commitment to consumer protection, we fully intend to dispute the conclusions” of the regulator’s report and associated fine, the representative said.

Last week, the FCC proposed fines totalling more than $200 million for the top four US operators, alleging their practice of selling subscriber location data with third parties violated data privacy regulations.

T-Mobile faces a potential fine of $91 million and AT&T $57 million. However, the FCC noted all four companies would have a chance to respond to the allegations before the penalties are finalised.

A Sprint representative told MWL it is still in the process of reviewing the FCC’s findings.