1. A method for operating a mobile terminal, the method comprising: performing voice recognition on incoming and outgoing call content to produce recognized call content after the call is established; converting the recognized call content into one or more units of character information; registering the one or more units of character information to one or more particular functions of the mobile terminal based on a type of the character information or a field of the character information; receiving an input of a search parameter; searching one of a plurality of file types and identifying a file related to both the search parameter and the one or more registered units of character information; and displaying or automatically executing the identified file.