Without wanting to confuse you completely, let us explain. An ordinary phone system relies on what is known as the public switched telephone network (PSTN) otherwise known as POTS – the plain old telephone system which has existed since 1876 and which remains the basic form of residential and small business service connection to the telephone network in many parts of the world.
Since the inception of the internet, telephones and technology have moved on exponentially and we now have IP telephony or Voice over Internet Protocol commonly known as VoIP.