Performance monitoring of DSO channel via D4 channel bank

Non-intrusive performance monitoring of a DS0 channel between a customer premises interface and a D4 channel bank includes an augmentation of existing channel bank equipment and a digital services communication device terminating the DS0 link at the customer site. An auxiliary signalling and performance monitoring arrangement is remotely accessible by a non-resident control site, for example by way of an RS-232 port of a line interface unit of the channel bank, thereby enabling the control site to perform prescribed network supervisory tasks with respect to one or more selected DS0 links, including provisioning of their associated loop equipment and performance monitoring of each DS0 loop. Office channel unit data port and line interface components of the channel bank are modified to provide bidirectional signalling capability via the receive segment of the channel bank's internal communications link. The signalling format on the bidirectional signalling link is defined so as to support both the transmission of incoming (received DS1) signalling traffic from the line interface unit to an office channel unit, and the bidirectional exchange of performance-monitoring command and response messages. A performance monitoring arrangement, installed in the channel unit and the digital communications network interface, monitors at least one prescribed performance aspect of the DS0 channel and forwards performance signals to the line interface unit over the bidirectional signalling link.