We are in the midst of a VoIP communications revolution.
What is special about VOIP is that it's just another thing you can do on the Internet, whereas it is the only thing - or nearly the only thing with the exception of the dial-up modem and fax - that you can do on the public switched telephone network.
Cisco has been both a pioneer in legitimizing VoIP as an alternative to traditional telephony but also an innovator as it has maintained its competitive lead over the past decade.