Abstract: An arrangement and method for providing a dial pulse muting function to prevent the sender outpulsing from being heard is to disable the sampling of the transmit to the network side of the trunk circuit which is connected through the time switch and to the receiver from the network side of the line circuit. This function takes place in the trunk circuit, rather than the line circuit, so that less equipment is required. The function, furthermore, is provided through the use of integrated circuit chips as opposed to relays so that less space is required and the arrangement is far more reliable.

Abstract: Generally, the power fail monitor and transfer circuit of the present invention provides four metallic transmission loops from the subscribers on the private branch exchange to four dedicated trunk lines to the central office. The central office battery is utilized as the transmission media and, on incoming calls, the central office extends ringing current directly to the private branch exchange subscribers. The metallic transmission loops are automatically provided during a failure, and, during power restoration, any interruption of existing telephone conversations is effectively prevented by monitoring the current flow in the transmission path, by means of optical couplers.