(1) Except as provided in ORS 759.265, no telecommunications utility or any agent or officer thereof shall, directly or indirectly, by any device, charge, demand, collect or receive from any person a greater or less compensation for any service rendered or to be rendered by it than:
(a) That prescribed in the public schedules or tariffs then in force or established; or
(b) It charges, demands, collects or receives from any other person for a like and contemporaneous service under substantially similar circumstances. A difference in rates or charges based upon a difference in classification pursuant to ORS 759.210 shall not constitute a violation of this paragraph.
(2) Any telecommunications utility violating this section is guilty of unjust discrimination.