 data. HISTORY OF IP IP stands for Internet Protocol. This is a standard set of instructions for communicating among comput- ers that was agreed upon by a group of universities in the 1960's. Supported by the United States' military for research and development, the original network was called ARPANET. They set up a network among them- selves to exchange information over telecommunica- tions circuits. This was the foundation of today's Internet supporting the World Wide Web. VoIP vs. Public Switched Telephone Network (PSTN) Calls As mentioned above, the term VoIP refers to voice com- munications using Internet Protocol. Most telephone calls are The Telecom Handbook - 143 CONVERGENCE OF VOICE & DATA currently made over what is sometimes called the PSTN or Public Switched Telephone Network, the network of circuits connected by the switching systems of the many local and long distance telephone companies worldwide. A voice con- versation on the PSTN requires an end-to-end connection that stays in place and uses up bandwidth on the circuit for the duration of the telephone call. During the call, the voice may be converted from analog to digital form and back to analog at the distant end. It is also possible to transmit and receive a voice conver- sation by breaking the voice transmission up into digital packets (groups of zeroes and ones) and sending it over a net- work in that form. In this scenario, the end-to-end type of connection used exclusively for the voice conversation on the PSTN is not required. The telecommunications carriers are migrating their net- works to IP enabling more efficient use of their network backbones. Unlike the PSTN, an IP network does not channelize high capacity telecommunications pipes (high ca- pacity circuits like T3's). The other big benefit of IP is that the intelligence is at the "edge" and the network is "dumb." A relatively simple router moves the packets to the next router and SO on until the packet gets to the right address. As such, IP networks are much cheaper than telephone