Dial switching of toll circuits in independent telephone company areas: Transmission considerations from the direct distance dialing standpoint

By the very nature of telephone traffic, any telephone subscriber may wish to be connected to any other subscriber in a continental area or possibly anywhere in the world. This implies switching of connections. It also implies switching these connections at more than one point since it would be economically impracticable to concentrate all switching operations at one point for even a single metropolitan area. With subscriber line switching on a decentralized basis, it naturally follows that switching centers themselves must be switched in order to accomplish economical interconnection of any two telephone subscribers.