Available numbers are numbers that are available for assignment to subscriber access lines, or their equivalents, within a switching entity or point of interconnection and are not classified as assigned, intermediate, administrative, aging, or reserved. Available numbers is a residual category that can be calculated by subtracting a sum of numbers in the assigned, reserved, intermediate, aged, and administrative primary categories from the total of numbers in the inventory of a code or block holder (FCC 00-104 §52. 15 (f) (1) (iv). )