A man was found guilty Thursday of assault in an attack sparked by a loud cell phone.

Anton Kirk, 19, savagely beat a man who asked him and his friend to lower the volume on their phone because it was bothering other NJ Transit passengers. Prosecutors said Kirk followed 26-year-old Jeffrey Cesario off the train in New Brunswick and, with the help of a 16-year-old friend, punched him in the face.

Cesario suffered a broken jaw in the incident.