AT&T (NYSE: T) has agreed to pay the U.S. government $700,000 to settle complaints that the company improperly switched certain customers to a mandatory wireless data plan. The company will also issue refunds to customers that could equal $25 to $30 a month, according to a news release from the Federal Communications Commission.

According to the FCC, the terms of some customers' service plans were changed, starting in November 2009, even though they were supposed to be able remain on pay-as-you-go data plans.

Michele Ellison, chief of the FCC's Enforcement Bureau, urged AT&T subscribers to "check their bills closely and contact the company if they spot any overcharges related to wireless data." The company is obligated to search out those it may have overcharged.

AT&T has also agreed to an "extensive" compliance plan, said the FCC, including consumer

notification, training of customer care representatives, and periodic compliance reports to the FCC.

Many of the issues came when customers who had pay-as-you-go data plans switched phones or moved to a new residence and were automatically charged on a monthly rate, despite the understanding that AT&T would "grandfather" in these situations, and continue to charge at the old rate, according to the FCC.