Idaho Code § 61-314
Every common carrier and every telephone corporation shall print and file or cause to be filed with the commission, schedules showing all rates, fares, tolls, rentals, charges and classifications for the transportation of persons or property or the transmission of messages or conversations between all points within this state and all points without the state upon its route, and between all points within this state and all points without the state upon every route leased, operated or controlled by it, and between all points on its route or upon any route, leased, operated or controlled by it within this state and all points without the state upon the route of any other common carrier or telephone corporation whenever a through route and joint rate shall have been established between any two (2) such points.
Idaho Code § 61-314