Abstract: An extension repeater which interfaces between a digital service network and a local network span combines extensive diagnostic and operational functions in a single, space-efficient device. The functions include simultaneous loopback capability in both the direction of the digital service network and the local network span, signal regeneration capability in both directions, non-intrusive monitoring connections for each side of the repeater, and visual indicators of the loopback states as well as the framing type of the data received from the digital service network and the local network span. Furthermore, the extension repeater is physically sized and shaped to fit in standard wall-mount telephone equipment shelves in order to provide economical and simplified installation of the repeater at locations outside of a telephone network central switching office.

Abstract: A subscriber's data circuit between channel bank and the customer premises carries fractional T1 bandwidth on a digital subscriber line (DSL) circuit. For example, for an ISDN rate digital subscriber line (IDSL), the circuit between the network termination at the customer premises and a D4 channel bank carries data on two combined B-channels. Such a circuit also carries a D-channel and an embedded operations channel (EOC), in normal ISDN fashion. A data service using such a line circuit, however, only transports the data (combined B-channels) through the network. The D-channel and the EOC are not carried through the network. To facilitate testing of the subscriber's circuit, the carrier operations and testing facilities transmit loop-back commands or the like in band to the channel bank. A command may be addressed to any active node along the subscriber's DSL circuit.