An Inregrated Line Continuity Test System for Four Wire Telephone Channels

This paper describes a system to cheek the continuity of a four wire "trunk" channel according to the CCITT recommendations. The test sequence is as follows: a loop connection is realized by the remote exchange while a 2 kHz tone is sent on one pair at the originating end. The test is successful when the tone is detected within suitable levels during at least SO ms (1).