New York- A businessman has dropped the dime on a gaggle of Gambino gangsters, agreeing to cooperate with prosecutors who want to nail them for running a phone-sex and Internet porn scam that swindled $730 million. Kenneth Matzdorff in Brooklyn federal court on Friday pleaded guilty to conspiracy, wire fraud and money laundering.

He joined a line of people who have agreed to cooperate in the prosecution of reputed Gambino soldier Richard Martino [pictured] and nine others tied to the crime family, said a source close to the case.

Matzdorff, a Peculiar, Mo., resident, was accused of being the puppet owner of a telephone billing company called USP&C that was in reality controlled by Martino and two Gambino associates.

USP&C allegedly was a key part of one of two massive schemes run by Martino from 1997 to 2001 that earned up to $600,000 a day.

In the first, customers who called “800” telephone numbers that advertised allegedly free samples of phone sex, horoscopes and dating services were whacked with a $40 fee that would automatically recur each month on their bills.

In the second scam, people who disclosed their credit-card numbers in exchange to verify their ages for a “free” tour of Internet porn sites were hit with $90 monthly charges.