T-Mobile logoT-Mobile customers should keep an eye out for identity thieves. The cell service provider said today that the data of about 15 million credit applicants was stolen from credit reporting agency Experian.

Applicants who had their credit checked for T-Mobile phone plans and financing between Sept. 1, 2013 through Sept. 16, 2015 may have had their Social Security numbers, home addresses, birthdates and other personal information revealed in the hack. While data like Social Security numbers and ID numbers were encrypted, Experian said that the encryption may have been broken.

T-Mobile CEO John Legere wrote a message to those affected, stating his anger at the situation and his dedication to protecting customer data.

I’ve always said that part of being the Un-carrier means telling it like it is. Whether it’s good news or bad, I’m going to be direct, transparent and honest.

I am incredibly angry about this data breach and we will institute a thorough review of our relationship with Experian, but right now my top concern and first focus is assisting any and all consumers affected. I take our customer and prospective customer privacy VERY seriously. This is no small issue for us. I do want to assure our customers that neither T-Mobile’s systems nor network were part of this intrusion and this did not involve any payment card numbers or bank account information.

After the hack was discovered, Experian alerted authorities and hasn’t seen any use of the stolen data yet. T-Mobile is providing two years of credit monitoring to affected customers.

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