Plain old telephone service

Plain Old Telephone Service (POTS), or Plain Ordinary Telephone System^[1], is a retronym for voice-grade telephone service that employs analog signal transmission over copper loops. The term POTS originally stood for Post Office Telephone Service, as early telephone lines in many regions were operated directly by local Post Offices. For instance, in New Zealand, the telephone system remained under Post Office control until the 1980s.

POTS was the standard service offering from telephone companies in the United States from 1876 until 1988^[2], when the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by the development of cellular telephone systems and voice over internet protocol (VoIP).

Despite the advent of these technologies, POTS remains a basic form of residential and small business connection to the telephone network in many parts of the world. The term encapsulates a technology that has been available since the introduction of the public telephone system in the late 19th century, remaining largely unchanged despite the introduction of innovations such as Touch-Tone dialing, electronic telephone exchanges and fiber-optic communication into the public switched telephone network (PSTN).