PSTN stands for "Public Switched Telephone Network" and is the traditional, circuit-switched telephone network used worldwide for voice communication.
It is based on an extensive infrastructure of fixed copper lines, fiber optic cables, mobile networks and satellite connections, which together form a global network for analog and digital voice transmission. PSTN enables the connection of telephone sets via a series of exchanges and circuits that route calls between subscribers. This system was originally developed for fixed-line telephony and offers high reliability and voice quality.
Despite the increasing use of VoIP (Voice over Internet Protocol) and other digital communication methods, PSTN remains an important basis for global telephone communication, especially in areas with limited access to internet services.