Hackers have stolen personal information from 15 million T-Mobile subscribers, the company announced on Thursday. The breach occurred through credit reporting agency Experian.

The hack affects applicants who required a credit check for service or device financing from Sept. 1, 2013, through Sept. 16, 2015. In a statement, Experian said the information the hackers obtained “included names, dates of birth, addresses, and Social Security numbers and/or an alternative form of ID like a drivers’ license number, as well as additional information used in T-Mobile’s own credit assessment.”