T-Mobile USA, Inc. disclosed that an unauthorized party accessed Experian servers housing T-Mobile data on September 15, 2015. The breach, occurring around September 14, 2015, involved the exfiltration of personal information including names, addresses, Social Security numbers, dates of birth, and government ID numbers. No payment card or banking information was compromised. T-Mobile and Experian notified law enforcement and offered two years of credit monitoring to affected individuals.