 These were uniquely designed for communications between the air traffic control tower and radar approach control (RAPCON) or ground control approach (GCA), and included radio line connections.Automatic Electric Company also produced a family of key telephone equipment, some of it compatible with Western Electric equipment, but it did not gain the widespread use enjoyed by Western Electric equipment.With the advent of LSI ICs, the same architecture could be implemented much less expensively than was possible using relays.