What are the four generic architectural components of a public communications network? define each term?

Like every telecommunication network, the public communication network consists of terminal nodes connected with each other through transmission links. Packet switching enables passing the signal through the correct links and nodes to reach the correct destination terminal.

The four generic architectural components are: S ubscribers (the devices at the end-users: telephones and modems), subscriber line (the transmission link between the subscriber and the network), exchanges (the switching centers in the network) and trunks: the branches between exchanges.