Jefferson City, Mo. – Hundreds of thousands of Missouri T-Mobile consumers who applied for credit through Experian could be at risk of having their data compromised.

That warning was issued Wednesday by Missouri Attorney General Chris Koster. He warns that those individuals should consider taking steps to protect their credit. According to Experian’s estimate, personal information of 263,000 Missourians was affected by the breach.

According to Koster, an unauthorized party accessed T-Mobile data housed on an Experian server, including consumer information. Affected customers are those who applied for T-Mobile USA postpaid services between September 1, 2013, and September 16, 2015. Information that was breached includes customers’ names, addresses, social security numbers, dates of birth, identification numbers (typically a driver’s license number, military ID, or passport number) and additional information used in T-Mobile’s own credit assessment.

Consumers who are affected should consider registering for a credit freeze with all three major credit reporting agencies as a precautionary measure, Koster said. Information about credit freezes is available on the Attorney General’s website at: http://ago.mo.gov/divisions/consumer/identity-theft-data-security/identity-theft-repair-checklist.

Consumers whose credit was checked by Experian for these T-Mobile services and who elect not to place a freeze on their credit file may wish to place a fraud alert on their file with all three credit reporting agencies. Information about fraud alerts is available here: http://www.consumer.ftc.gov/articles/0275-place-fraud-alert.

Experian and T-Mobile will offer affected consumers two years of credit monitoring and identity protection services at no cost. Credit monitoring alerts consumers to fraud after the fact, so Koster recommends having a credit freeze already in place to deter fraud.