A telecommunications system for providing both narrowband and broadband services to subscribers; sunscriber equipment; a shelf therefor; a replaceable lowpass filter unit; line termination equipment; network termination equipment and a telecommunications rack with a plurality of shelves having a redundancy featur

An architecture, as well as various components, of an asynchronous transfer mode (ATM) subscriber access multiplexer (ASAM) system can be implemented using an xDSL (x-Digital Subscriber Line) using DMT (Discrete Multitone) or CAP (Carrierless Amplitude Phase Modulation) between a plurality of subscribers and a corresponding plurality of line termination equipment in a shelf that also includes network termination equipment for connection to an ATM network. The line termination and network termination equipment are interconnected by a bus internal to the shelf for providing subscriber access. Separate lowpass filters are provided at each end of a twisted wire pair between the shelf and each subscriber equipment. A shelf can be used as a hub for connecting to a remote shelf that includes the line termination equipment for connection to subscribers. Although the internal bus of the shelf is shown in a non-redundant embodiment, an increased level of equipment protection can be provided by placing one half of a redundant equipment pair in one shelf and the other half in the other shelf and sharing network termination equipment between such shelves.