T-Mobile said it has notified law enforcement and federal agencies, which it did not name. The company said it did not expect the incident to have material impact on its operations. It said the data was first accessed on or around Nov. 25.
It also said at the time that it would spend $150 million through 2023 to fortify its data security and other technologies.
Prior to the August 2021 intrusion, the company disclosed breaches in January 2021, November 2019 and August 2018 in which customer information was accessed.
T-Mobile, based in Bellevue, Washington, became one of the country’s largest cellphone service carriers in 2020 after buying rival Sprint in 2020. It reported having more than 102 million customers after the merger.