Nearly 15 million T-Mobile wireless users faced hacking of data including their personal information from the servers of Experian, a credit rating agency.

Experian on Thursday admitted that hackers have stolen personal information belonging to nearly 15 million T-Mobile wireless customers and potential customers in the U.S., including Social Security numbers, home addresses, birthdates and other personal information.

T-Mobile, the #3 telecom network operator, uses credit reporting agency Experian to check the credit of consumers applying for phone plans and financing for devices. Experian said T-Mobile customers who applied between Sept. 1, 2013 and Sept. 16, 2015 may have had their information stolen.

“We take privacy very seriously and we understand that this news is both stressful and frustrating. We sincerely apologize for the concern and stress that this event may cause,” said Craig Boundy, chief executive officer of Experian North America.

Experian is in the process of notifying consumers that may be affected, and safeguarding their identity and personal information by offering two years of credit monitoring and identity resolution services through ProtectMyID.

To find additional information, customers can go to www.experian.com/T-MobileFacts. Though there is no evidence to-date that the data has been used inappropriately, Experian encourages affected consumers to enroll in the complimentary identity resolution services. Affected consumers may enroll in free credit monitoring services at www.protectmyid.com/securityincident.

T-Mobile customers can sign up for two free years of credit monitoring services at www.protectmyID.com/securityincident , a service owned by Experian.

T-Mobile CEO John Legere, who is active on Twitter, responded to many tweeters unhappy with the resolution offered, AP reproted.

“I hear you re: Experian as service protection option. I am moving as fast as possible to get an alternate option in place by tomorrow,” Legere wrote Thursday evening.

Earlier in a statement, Legere had said that he was incredibly angry about the breach and that the company would review its relationship with Experian.

The hack happened on Experian’s server and is still being investigated, said Annie Garrigan, a spokeswoman for Bellevue, Washington-based T-Mobile.

Experian said in a statement on its website that it doesn’t know who was behind the hack and that it is taking necessary steps to prevent further breaches.

The company said that affected customers should remain vigilant against identity theft and watch for phishing email scams that ask for sensitive information such as bank account and Social Security numbers.

Nearly 800 data breaches were reported last year by U.S. organizations, according to the Identity Theft Resource Center.

Baburajan K
[email protected]