Wash. Rev. Code § 80.36.080
All rates, tolls, contracts and charges, rules and regulations of telecommunications companies, for messages, conversations, services rendered and equipment and facilities supplied, whether such message, conversation or service to be performed be over one company or line or over or by two or more companies or lines, shall be fair, just, reasonable and sufficient, and the service so to be rendered any person, firm or corporation by any telecommunications company shall be rendered and performed in a prompt, expeditious and efficient manner and the facilities, instrumentalities and equipment furnished by it shall be safe, kept in good condition and repair, and its appliances, instrumentalities and service shall be modern, adequate, sufficient and efficient.
RCW 80.36.080