Central Office (CO)

Central office is an ambiguous term in North America. It can mean a telephone company building where subscribers' lines are joined to switching equipment for connecting other subscribers to each other, locally and long distance. Sometimes, that central office means a wire center in which there might be several switching exchanges. That means there will be switches, cable distribution frames, batteries, air conditioning and heating systems, etc. But a central office is sometimes simply a single telephone switch, what Europeans call a public exchange. In short, you need to figure out by the context if central office means a building or a switch, or a collection of switches.