20:10:28:63Interexchange cable and wire facilities -- Category 3 -- Apportionment of cost.

An average interexchange cable and wire facilities cost per equivalent interexchange telephone circuit mile for all circuits in category 3 is determined and applied to the equivalent interexchange telephone circuit mileage counts of each of the classes of circuits. The cost of cable and wire facilities applicable to this category is directly assigned where feasible. If direct assignment is not feasible, the cost is apportioned between toll and other services on the basis of conversation-minute miles as applied to toll message circuits or other classes of circuits.

Source: 19 SDR 111, effective January 31, 1993.