table 150 it then determines from the data stored therein whether the status of all of the lines loop pairs forming anyone of the cables listed in table 150 is still unknown if das 25 finds that one or more such cables are listed in table 150 then das 25 directs switch 10 to perform an alit i e directed alit on one line of unknown status in each of those cables if a line passes the alit then the status of the line is marked 34 working 34 in table 125 otherwise the line is placed out of service and its status is marked as being in 34 trouble 34 das 25 also updates the corresponding data listed in table 150 following such alits das 25 checks table 150 to see if one or more cables listed therein has only one line whose status is known if das 25 finds that to be the case then it instructs switch 10 to perform an alit on one line of unknown status in each such cable similarly das 25 updates tables 125 and 150 to include the data derived from the latter test s das 25 continues in this manner calling for alit tests until it knows the status of a majority of the wire pairs forming a cable it is noted that during the time that such alits are being conducted table 125 is still being updated using the data that is contained in the roh and oos tables maintained by switch 10 and results obtained from other sources when the directed alits have been completed and das 25 has updated tables 125 and 150 then das 25 using table 150 estimates the total damage to the outside loop plant such estimating is done by multiplying the ratio of the.