Public Switched Telephone Network
The Public Switched Telephone Network (PSTN) is the global circuit-switched telephone network that has been in use since the late 1800s, enabling voice communication over copper wires, fiber optics, and wireless links. It provides traditional landline telephone services, connecting calls through a hierarchical system of switches and exchanges to route communications worldwide. While originally analog, modern PSTN has largely transitioned to digital technologies, integrating with internet protocols in many regions.
Developers should learn about PSTN when working on telecommunications systems, legacy infrastructure integration, or voice-over-IP (VoIP) solutions that interface with traditional phone networks. It is essential for understanding call routing, signaling protocols like SS7, and regulatory compliance in telephony applications, such as emergency services (e.g., 911/112) or business phone systems that require PSTN connectivity for reliability and broad accessibility.