It may not be the Philharmonic in the park, but that theme from "Mission: Impossible" blaring from your cellphone is a public performance — so pay up, a music trade group demands in a new lawsuit.

The American Society of Composers, Authors and Publishers, which protects performance rights for music artists, is suing cell carriers for a 2 percent cut of all ringtone sales — a charge that experts say will be passed on to customers.

The suit in Manhattan federal court claims that a phone ringing with snippets of popular music is equivalent to a public broadcast and therefore not just annoying but an infringement of copyright.

"This is a desperate move," said Fred von Lohmann, an attorney with the Electronic Frontier Foundation. "If in fact it is illegal for your phone to ring in public without a license, it's also illegal for you to play your radio with the window rolled down."

Though a Manhattan federal judge in 2007 ruled against ASCAP on the issue, the group appealed and is now trying to squeeze performance fees out of cellphone users the same way ASCAP goes after bars and restaurants that play recorded music, von Lohmann said.

"Ringtones are a roughly $300 million business in this country and they want a piece," he said.