(CNN) Thousands of AT&T customers are set to receive a refund from the company.

The Federal Communications Commission (FCC) has ordered the telecommunications corporation to pay $7.75 million, saying it allowed scammers to charge its customers $9 a month for a directory assistance service that didn’t exist.

AT&T is expected to refund a total of $6.8 million to customers and $950,000 to the U.S. Treasury.

Investigators believe the sham targeted mostly small businesses. They were charged for a monthly directory assistance service on their local landline telephone bills, but there was no service.

AT&T received a fee from the companies for each charge placed on its customers’ bills.

The company said it plans to send refund checks to consumers within 90 days.