Idaho Code § 61-513
Whenever the commission, after a hearing had upon its own motion or upon complaint, shall find that a physical connection can reasonably be made between the lines of two (2) or more telephone corporations whose lines can be made to form a continuous line of communication, by the construction and maintenance of suitable connections for the transfer of messages or conversations, and that public convenience or necessity will be subserved thereby, or shall find that two (2) or more telephone corporations have failed to establish joint rates, tolls or charges for service by or over their said lines and that joint rates, tolls or charges ought to be established, the commission may, by its order, require that such connections be made, and that conversations be transmitted and messages transferred over such connection under such rules and regulations as the commission may establish, and prescribe through lines and joint rates, tolls and charges to be made, and to be used, observed and in force in the future. If such telephone corporations do not agree upon the division between them of the cost of said physical connections or connections of the division of the joint rates, tolls or charges established by the commission over such through lines, the commission shall have authority after further hearing, to establish such division by supplemental order.
Idaho Code § 61-513