Abstract: There is disclosed an apparatus for interconnecting a plurality of communications mediums, including voice frequency and broadband frequency to a subscriber communications system at the subscriber's premises. The apparatus comprises: 1) a controller for coupling and de-coupling communications mediums comprising at least one public service telephone network (PSTN) line and at least one non-public service telephone network (non-PSTN) line, to a communication system within the subscriber's premises; 2) lightning protection for controller interfaces; 3) a detector circuit for detecting power loss in the non-public service telephone network connection and 4) fail-over (re-connecting to an alternate circuit) devices connected to a public service telephone network line; and 5) a test circuit for monitoring the condition of a backup power supply for the apparatus.