What is PSTN?

• PSTN (public switched telephone network) is the world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned. It's also referred to as the Plain Old Telephone Service (POTS). It's the culmination of circuit-switching telephone networks that has evolved from the days of Alexander Graham Bell ("Doctor Watson, come here!"). Today, it is almost entirely digital in technology except for the final link from the central (local) telephone office to the user.
  
  
• The basic PSTN network link, or POTS line supports 64 Kbps bandwidth. In residences, the phone line carrying this bandwidth is typically a copper cable. Traditional dial-up modems utilize nearly 56 Kbps of this bandwidth when connected to a phone line. The PSTN utilizes the SS7 signaling protocol.
  
  
• The PSTN also serves as the primary backbone for connecting Internet Users to the World Wide Web.