Definition
PSTN connectivity refers to the use of the Public Switched Telephone Network, the traditional global system of interconnected voice-oriented telephone networks, to transmit data. It operates by converting digital data into analog signals that can travel over analog phone lines, and then converting them back to digital at the receiving end. Understanding PSTN connectivity is crucial for IT professionals as it enables communication and data transfer in scenarios where IP networks are unavailable or unreliable. For instance, dial-up modems historically used PSTN lines to connect computers to the internet. This differs from modern IP-based communication, which uses packet switching over digital networks. Knowledge of PSTN connectivity is relevant for certain networking and security certifications.