Two years ago, SpoofCard suspended Paris Hilton's account after gossip sheets linked her to the voicemail hacking of her celebrity rival, Lindsay Lohan. At the time, SpoofCard said it had suspended more than 50 customers for using the service to hack into voicemail accounts.

As part of Thursday's settlement, AT&T will pay US$59,300 in penalties; T-Mobile will pay $25,000. The case was heard in the Superior Court of the State of California for the County of Los Angeles.

In a separate civil action, SpoofCard's parent company TelTech Systems has agreed not to advertise its product as "legal in 50 states." It is not legal in California and some other states, the district attorney's office said. TelTech will also pay a $33,000 fine.

AT&T and TelTech did not immediately return calls seeking comment.