Three Sony music acts are suing the music label for allegedly stiffing them on revenue sharing from legal download services and now ringtones, too. Internet downloads that sell for 99 cents bring in a mere 4.5 cents in royalties. The artists say they should get 30 cents in a licensing deal. Ringtones have been nearly twice as lucrative at 8.3 cents a piece, but compare that to the $1 to $1.50 Sony gets per sale. The musicians want 50 cents to 75 cents. The plaintiffs have asked a Manhattan court to certify the case with class-action status for other Sony artists who signed on between 1962 and 2002. The lawsuit also predicts the ringtone market will be a $20 billion industry by the end of 2006. Article