Abstract: A telephone system including a switching circuit (3) connected to a plurality of extension telephone sets (1-1 to 1-n, 1-p) a plurality of office lines (4-1 to 4-m) for selectively connecting the respective extension telephone sets and the respective office lines, a control unit (6) for connecting an extension telephone set and an office line through the switching circuit (3), a main memory (8) for registering the extension telephone sets diverted into respective terminating call dedicated telephone sets. When a key provided at an extension telephone set is pressed in a predetermined process to input a data for diverting the extension telephone set into a terminating call dedicated telephone set, the control unit (6) registers the extension telephone set into main memory (8).

Abstract: A printed-circuit board, mounted inside the plastic housing of a piece of electrical equipment adjacent to a hole in the housing, has a ground trace adapted to be connected to a source of ground potential. The ground trace is positioned on the printed-circuit board so that, when the board is mounted in the housing, a portion of the ground trace is the nearest conductor to the hole. In this way, static discharges through the hole are prevented from damaging the equipment.