In the switched telephone world, what we know as POTS (plain old telephone service), telephone calls are placed from copper wire pairs at the premises, to copper pairs, to the call’s recipient. In a total VoIP world, voice is converted to data packets and routed over IP, sometimes over the public Internet, then converted back to voice.
It is rapidly becoming a new world of communications where VoIP is a “disruptive†technology redefining telephone service, much like how the automobile was disruptive to the horse and buggy.