The answer to your first question is yes. Each department on a frequency has it's own unique tone, so that their pagers will be the only ones to activate when they get a call. Some departments may have more than one tone, if they have multiple stations they would have a tone for each station, and possibly a "master tone" that would alert every station without having to alert them all one at a time. Some departments have a tone for on-duy personnel only and another one for all personnel.
Not sure about Jackson, though, as I don't listen to them very much.