Plain Old Telephone Service (POTS)

Techopedia explains Plain Old Telephone Service (POTS)

Plain old telephone service is a voice grade telephone service. It continues to be the basic form of home and small business service connection to telephone networks around the globe. POTS includes bidirectional or full duplex voice band paths with frequencies limited to 300 to 3400 hertz (cycles per second). POTS also includes call progress tones such as dial tones and ringing signals, subscriber dialing, operator services such as directory assistance and long distance calling, and a standards compliant analog telephone interface.

The computerization of telephone exchanges in the '70s and '80s made features such as voice mail, call waiting, caller ID, enhanced 911, Centrex and speed dialing available to subscribers. The extensive availability of POTS allowed new forms of communication devices, such as modems and facsimile machines, to use POTS for digital information transmission.