Plain old telephone service

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Plain Old Telephone Service (POTS), or Plain Ordinary Telephone System,^[1] is a retronym for voice-grade telephone service employing analog signal transmission over copper loops. Originally POTS stood for Post Office Telephone Service as early phone lines in most parts of the world were operated directly by the local Post Office. (For instance, in New Zealand the telephone system was owned and operated by the Post Office as recently as the 1980s.)

POTS was the standard service offering from telephone companies from 1876 until 1988^[2] in the United States when the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by cellular telephone systems, and voice over IP (VoIP). POTS remains the basic form of residential and small business service connection to the telephone network in many parts of the world. The term reflects the technology that has been available since the introduction of the public telephone system in the late 19th century, in a form mostly unchanged despite the introduction of Touch-Tone dialing, electronic telephone exchanges and fiber-optic communication into the public switched telephone network (PSTN).