No telecommunications company shall make or give any undue or unreasonable preference or advantage to any person, corporation or locality, or subject any particular person, corporation or locality to any undue or unreasonable prejudice or disadvantage in any respect whatsoever. The commission shall have primary jurisdiction to determine whether any rate, regulation, or practice of a telecommunications company violates this section. This section shall not apply to contracts offered by a telecommunications company classified as competitive or to contracts for services classified as competitive under RCW 80.36.320 and 80.36.330.