The term POTS originally stood for post office telephone service,[citation needed] as early telephone lines in many regions were operated directly by local post offices.
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.
This is an often cited benchmark in marketing and systems-engineering comparisons, called the "five nines" reliability standard.
Many new housing developments are being offered which do not have such a connection so these homes depend upon a VOIP non-hardwired linkage to the phone company.