Abstract: A three-ported apparatus is adapted to interface a serial TDM bus, a local controller and a line unit bus in a telecommunications terminal. All data passing between the TDM bus and the line unit bus is temporarily stored and is accessible to the local controller, allowing the controller to either pass said data without modification or provide modifications thereto. Signaling contained within the data may be translated to a form usable by the line unit through the use of translation tables down-loaded from inventory storage on the line units. For each line unit, the local controller programmably controls time slot assignment, provisioning and inventory information access.