The Public Switched Telephone Network, or PSTN, is the traditional network used for telephone communication. It consists of a vast system of interconnected telephone lines, fiber optic cables, and switching centers that enable voice calls between landline and mobile phones. PSTN operates using circuit-switching technology, which establishes a dedicated communication path for the duration of a call. PSTN has been the backbone of global telecommunication for over a century. While newer technologies like VoIP (Voice over Internet Protocol) are becoming more popular, PSTN remains essential for reliable voice communication, especially in areas with limited internet access.