An XDSL system may include an active unit and a standby unit. The active unit may include a plurality of line circuits, which can be used to form XDSL loops with far end units. The standby unit may be synchronized with the active unit. In response to an indication, such as a fault, the TDM system may switch from the active unit to the standby unit. Then, the standby units may be used to form the XDSL loops with the far end units.