Arrangement for testing telephone subscriber line circuit via B-ISDN channel linking central office test system and metallic channel unit installed in digital loop carrier remote terminal

摘要

A subscriber line circuit test and conditioning arrangement for use with a non-metallic (fiber optic) digital communication path-based digital communication network employs a single (basic rate ISDN) metallic channel unit (BMCU) installed at a site terminating the fiber optic communication path. A BMCU communicates with a central office test system using an auxiliary B-ISDN communication 'test' channel portion (2B+D) channels of the time division multiplexed digital communication DS0 channels. Digital command and response signals are transported by the two ISDN bearer (B) channels and are coupled directly to tip and ring digital signal processors in the central office test system, without the need for intermediate digital-to-analog and analog-to-digital conversion by a metallic channel unit at a central office terminal, and that additionally performed by a central office terminal and central office switch. The data (D) channel is employed to conduct access, calibration and control communications with the metallic channel unit.