Plain old telephone service

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Plain old telephone service (POTS), or rarely publicly offered telephone service, is a retronym for voice-grade telephone service that employs analog signal transmission over copper loops. 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). POTS was the standard service offering from telephone companies in the United States until c. 1988, 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). POTS has largely been phased out in many developed regions, though it remains in limited use in rural areas and legacy applications, including systems such as fire and...

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