Technological innovation is hurling itself upon us once again.This time it’s coming in the form of improving the way we communicate, bringing with it new capabilities that change the meaning of the phrase telephone call.
VoIP (often pronounced “voyp”) is the name of this new communications
technology.

VoIP, which stands for voice over Internet protocol, basically means voice
transmitted over a digital network. Well, that isn’t technically accurate
because the Internet isn’t strictly necessary for VoIP, although it was at first.
What is necessary for VoIP technology is the use of the same protocols that
the Internet uses. (A protocol is a set of rules used to allow orderly communi-
cation.) Thus, voice over Internet protocol means voice that travels by way of
the same protocols used on the Internet.

VoIP is often referred to as IP telephony (IPT) because it uses Internet protocols
to make enhanced voice communications possible. The Internet protocols
are the basis of IP networking, which supports corporate, private, public,
cable, and even wireless networks. VoIP unites an organization’s many
locations — including mobile workers — into a single converged communica-
tions network and provides a range of support services and features
unequalled in the world of telephony.

Technically, IPT refers to telephone calls carried over the organization’s local
area network (LAN) such as a single building location, a campus-like network,
or even a LAN within your home. When IPT crosses from the LAN to the WAN
or any other external network, including other LANs operated by the same
company at distant locations or the Internet, it becomes VoIP.



Before digital networking took off, everyone had to use the one and only
POTS, which stands for plain old telephone service (honestly, it does). POTS
runs over a network called the PSTN, or public switched telephone network.
These POTS telephone systems use the tried-and-true method of telephone
service known as circuit-switched. (See Chapter 2 for more about the history
of POTS, the PSTN, and the operation of circuit-switched telephony.)

For customers, the costs related to the regulated circuit-switched PSTN
remain much higher than they need to be. Consumers as well as companies
that must rely on POTS on a daily basis know what the POTS way of tele-
phony means to their bottom line. The good news is that VoIP is an alterna-
tive that can greatly reduce or eliminate POTS-related costs. (Chapter 3 fully
details the recurring charges of the POTS way of doing telephony.) VoIP also
enhances productivity, leaving more money in the budget to do other things
besides pay telephone bills.

VoIP technology enables traditional telephony services to operate over com-
puter networks using packet-switched protocols. Packet-switched VoIP puts
voice signals into packets, similar to an electronic envelope. Along with the
voice signals, the VoIP packet includes both the caller’s and the receiver’s net-
work addresses. VoIP packets can traverse any VoIP-compatible network.
Because VoIP uses packets, much more information can be carried over the
network to support and enhance your communication needs when compared
to traditional telephony methods.

In a circuit-switched network such as POTS, routing is less dynamic than with
a packet-switched network. In the POTS world, if a line is down, the call can’t
go through. In a packet-switched network, multiple routes can be established,
and packets can travel any of the available routes. If one of the lines support-
ing the network is down, the packet can switch to another working route to
keep the call up.

With VoIP, voice signals can travel the same packet-switched network infra-
structure that companies already use for their computer data. Chapter 7 goes
into more detail about dedicated packet-switched networks that support VoIP.