Idaho Code § 61-323
No telephone corporation subject to the provisions of this act shall charge or receive any greater compensation in the aggregate for the transmission of any long distance message or conversation for a shorter than for a longer distance over the same line or route in the same direction, within this state, the shorter being included within the longer distance, or charge any greater compensation for a through service than the aggregate of the intermediate rates or tolls subject to the provisions of this act; but this shall not be construed as authorizing any such telephone corporation to charge and receive as great a compensation for a shorter as for a longer distance. Upon the application to the commission a telephone corporation may, in special cases, after investigation, be authorized by the commission to charge less for a longer than for a shorter distance service for the transmission of messages or conversations, and the commission may from time to time prescribe the extent to which such telephone corporation may be relieved from the operation and requirements of this section.
Idaho Code § 61-323