Abstract: A communication bridge joining a primary communication channel to a plurality of secondary communication channels has electrically operated switches in series with the respective ports to the secondary communication channels. Control signals applied to the primary channel are utilized to address the bridge and to selectively drop or add secondary ports. Additionally a loopback circuit can be connected and disconnected in the primary port.

Abstract: DTMF (dual-tone multi-frequency) activated apparatus for remote switching and testing of a four-wire telephone line system is disclosed. The telephone line provides four-wire service between a first location and a plurality of second remote locations. By using a standard twelve button or expanded sixteen button telephone DTMF key pad, the switching and testing apparatus provides the capability at the first location of controlling switching circuits at any one of the remote locations. Each remote switching and testing circuit is provided with a DTMF detector and digital logic responsive to the detector for recognizing an assigned address code and any one of the command codes corresponding to the looped mode, the terminated mode, the milliwatt source mode, and the in-data mode. A programmable three digit address, for example, allows use of up to one thousand switching and testing circuits on one line.

Abstract: Apparatus for remote switching and testing of a four-wire telephone line system is disclosed. The telephone line provides four-wire service between a first location and one or more second remote locations. The switching and testing apparatus provides the capability at the first location of controlling switching circuits at the remote location and making tests of the telephone line system including customer installed equipment. The telephone line, which will include a dedicated transmission path through at least one telephone company central office, is terminated at the respective customer premises by a terminating unit which provides a connection of customer installed equipment to the four-wire line.