Abstract: A replaceable plug which provides voltage surge protector redundancy for use in a maintenance termination unit connecting a telephone company line to a subscriber telephone line. The plug includes connecting terminals for connecting input and output telephone lines to a switch within the plug, and a pair of surge protector circuits. The switch is wired so that it selectively connects one or another of two surge protectors between the input and output lines replacing an actuated protector with a back up protector and restoring telephone service to the subscriber. Associated with this device is a method of determining whether a telephone line fault is due to a protector actuation or in the line proper, and for restoring telephone service without having to send a service person to the location of the maintenance termination box, by providing surge protector redundancy and a switching arrangement whereby a protector is replaced in the line circuit by a switching action.

Abstract: A replaceable plug which provides voltage surge protector redundancy for use in a maintenance termination unit connecting a telephone company line to a subscriber telephone line. The plug includes connecting terminals for connecting input and output telephone lines to a switch within the plug, and a pair of surge protector circuits. The switch is wired so that it selectively connects one or another of two surge protectors between the input and output lines replacing an actuated protector with a back up protector and restoring telephone service to the subscriber. Associated with this device is a method of determining whether a telephone line fault is due to a protector actuation or in the line proper, and for restoring telephone service without having to send a service person to the location of the maintenance termination box, by providing surge protector redundancy and a switching arrangement whereby a protector is replaced in the line circuit by a switching action.