Network and infrastructure
Local loop
The local loop links a subscriber to the operator's first equipment: historically a pair of copper wires from the premises to the exchange.
It is the most expensive segment of the network, because it is shared with nobody: every subscriber has their own. It also decides what a device plugged in at your end can do. While it stays copper, the loop carries a continuous analogue signal that a fax machine understands. Replaced by fibre, it carries packets — and the analogue device no longer speaks the network's language.