Staffer fired as customers notified of personal data access.
AT&T has begun notifying its customers about the data breach by one of its employees, discovered in August.
The employee gained unauthorized access to users’ personal data.
The company has informed around 1,600 customers about the data breach, sources familiar with the matter told Reuters.
AT&T said that the employee has been fired, and the company has notified the Federal authorities about the incident.
In a letter written to the Attorney General of Vermont, the company said the accused person might have gained access to the driver’s license numbers, social security numbers and information about AT&T services that customers subscribed to.
AT&T spokesman said: "Unfortunately, we recently learned that one of our employees did not follow our strict privacy rules and inappropriately obtained some customer information.
"This individual no longer works at AT&T and we are directly contacting the limited number of affected customers."
AT&T has not disclosed the exact number of customers affected by the data breach.
The company said it would reverse any unauthorized charges or changes that might have resulted to customer accounts due to the breach. It has recommended the users to change their passcodes, and also review their credit reports.