Date Added: Jan 2013
Internet telephony services are voice, fax, SMS applications that are transported via the Internet. The steps are originating a VoIP telephone call and media channel setup, digitization, packetization, and transmission as Internet Protocol (IP) packets over a packet-switched network. On the receiving side, similar steps there are many organizations like Skype, Google talk etc, providing VoIP. VoIP systems employ session control protocols to control the setup and tear-down of calls as well as audio codec which encode speech allowing transmission over an IP network as digital audio via an audio stream.