A Montana man has been sentenced to two years in prison after prosecutors said his companies tricked people across the nation into paying as much as $70 million in unauthorized charges on their phone bills.

U.S. District Judge Dana Christensen also ordered Steven Sann of Stevensville to forfeit $500,000 on Friday.

Sann pleaded guilty in April to wire fraud and money laundering.

A Federal Trade Commission investigation found the 59-year-old Sann ran nine companies involved in the practice known as cramming, which places unauthorized charges on phone bills.

Investigators say customers unwittingly signed up for voicemail accounts or fax services while answering questions on websites offering free products or job assistance.

Most customers didn't realize they were being charged between $10 and $25 a month for the services.