The U.S. Department of Labor has ordered cell phone company T-Mobile USA to pay a fired whistleblower more than $345,000.

The department announced Thursday the order resulted from an investigation into alleged violations of federal whistleblower protection laws.

The fired employee had raised concerns about "the possibility of millions of dollars in fraudulent roaming charges being levied on hundreds of international corporate customers." The employee was fired in 2009.

Bellevue, Wash.-based T-Mobile says it will appeal the order, adding that it will furnish evidence showing it terminated the employee within the confines of the law.

T-Mobile, a subsidiary of the Germany-based Deutsche Telekom AG, was also ordered to reinstate the employee. The order includes $244,479 in back wages and interest, $65,000 in compensatory damages and $36,493 in attorney's fees.