According The Gallatin County Sheriff’s Office -

They have been made aware of a recent string of scams that have occurred locally.  Scammers are calling local residents from a 406 area code and identifying themselves as law enforcement officers from various agencies, specifically the Gallatin County Sheriff’s Office.  They advise the victims that they have missed jury duty, and are subject to arrest if they do not pay related fines.  This is a scam. Do not send any money or give out any personal information.