Customers who signed up for the service between Sept 1, 2013 and Sept. 16, 2015 have had their information stolen from the credit bureau Experian, CNN Money reported.
The company used Experian to do credit checks on its customers. Hackers broke into the company’s server, taking 15 million people’s names, addresses, Social Security numbers, birthdays and other identification numbers.
Not all of the victims of the hack were customers of T-Mobile, which responded to the hack on its website.
T-Mobile’s CEO John Legere said he was ‘incredibly angry’ about the breach, The Associated Press reported.
‘Obviously I am incredibly angry about his data breach and we will institute a through review of our relationship with Experian, but right now my top concern and first focus is assisting any and all consumers affected,’ Legere said in a statement.
Legere also reached out to concerned customers on Twitter.
Experian notified law enforcement as soon as the hack was discovered and said that it doesn’t appear that the information has been used illegally, The AP reported.
Read more: Clark’s Identity Theft Guide
Affected customers can sign up for two years of free credit monitoring at Experian-owned ProtectMyID.com.