The commercial telephone service was born in 1877 and, from the outset, adopted a structure based on a multitude of switch board seach of which collected users from a restricted area and was in some way connected to all the others.
In a telephone network we can distinguish:
In the structure now almost universally adopted for the distribution network, the geographical area pertaining to a local power plant, called the power plant area, is divided into various cable areas, along different routes, each served by a single high-capacity cable, traditionally in copper.
In urban areas, multiple cables can go out along the same route, serving different areas. Each cable feeds along its path several distribution cabinets, each destined to distribute the outgoing pairs towards the user in a specific cabinet area. In correspondence with the cabinets, which constitute points of flexibility in the network, it is possible to install numeric user collection systems (user multiplexers). From the cabinet to the
users there is an additional point of elasticity constituted by the distribution box or distributor.
So in a copper distribution network we distinguish several elements:
In the hundred years since the birth of telephony, the distribution network has undergone a relatively slow evolution. The current network, although renewed in materials, is not so very different from that of a few dozen years ago.
The basic aspect that must be kept in mind when creating a distribution network is to make available to each user the necessary carrier for the service requested with the minimum cost, but with resources that can cope with demand development over time, and in space, not known a priori.
Understanding the architecture of the copper distribution network is important because it is precisely on this that, in the last twenty years, the provision of Digital Subscriber Line (DSL) services to users has been based.