ATIS T1.TR.37-1994

This Technical Report describes a Line Break Detection functionality to detect a break in an access line between equipment located in the network and the customer installation (CI). The methodology is based on maintaining synchronization between the CI and the first network element by using a 40 Hz carrier that is BPSK (binary phase-shift keying) modulated at 20 baud. For maximum security, the carrier is digitally encoded with one of 255 pseudo-random sequences. At the time of installation, the first network element is trained to recognize only one of these pseudo-random sequences.