What is the primary function of the Public Switched Telephone Network (PSTN)?

The primary function of the Public Switched Telephone Network (PSTN) revolves around its role in connecting voice-oriented systems, which encompass traditional telephone communications. The PSTN is a global network that has historically been the backbone for conventional voice calls, allowing users to connect their calls through a series of switching centers and exchanges. This interconnectedness enables people to communicate across various distances using standard telephone lines, ensuring reliable voice transmission.

In this context, the focus on voice communications highlights that the PSTN is specifically designed for handling voice signals, not necessarily data or modern communication modalities like video calls or internet services. The technology and infrastructure of the PSTN prioritize durability, accessibility, and the structuring of voice calls, which is why connecting commercial and government voice-oriented systems aligns directly with its primary function.

Other provided options pertain to services or functionalities that have evolved with the advent of digital technology and the internet. While they reflect important aspects of modern communication, they do not encapsulate the fundamental purpose of the PSTN.