PHOENIX -- Federal prosecutors on Thursday announced criminal charges against more than two dozen people accused of stealing tens of millions of dollars from a telephone service for the deaf.

Authorities said owners and employees at seven companies schemed to create bogus calls to a video service that allows the deaf to converse over phone lines to hearing people. Together, the companies represent about 15 percent of the market for such services, according to Justice Department officials.

In Arizona, six people were arrested and made their initial appearance in federal court Thursday. All were released on a promise to appear in court in New Jersey next month.

Arrests were also made in Florida, Maryland, Nevada, New Jersey, New York, Oregon, Pennsylvania, and Texas.

The service is paid for by funds raised through charges on telephone bills, and the fund is overseen by the Federal Communications Commission. It allows deaf Americans to connect to a video service with a sign language translator, who can then relay information between a deaf person and a hearing person.

"With growth in technology came a crime of opportunity," said Joseph Persichini, head of the FBI's Washington field office.

The fund pays about $6 a minute to companies that provide the service, and the indictments charge the suspect firms struck deals with call centers around the country to make long calls to the service for about $2 a minute.

While the investigation continues, the FCC has stopped payment for about 2 million minutes, worth more than $12 million in charges.

The FCC also plans to put in new safeguards to prevent such rampant abuse in the future, officials said.

Persichini did not rule out more charges, and urged anyone with information about such fraud to come forward.

"I suggest they call us before we call them," Persichini said.