If you have an ear open to new computer technologies
you are sure to have heard about VoIP. Voice over
Internet Protocol (VoIP) is an emerging set of
applications which allows you to make telephone calls
over the Internet. It is already starting to replace
existing telephone networks, with some people and businesses
opting to cancel their traditional phone line and use
VoIP instead.

VoIP was originally developed to provide voice
communication between computer users in different
locations. Although it still has this application,
it has been further developed into a telephone network
in its own right. People using VoIP can call any
telephone anywhere in the world and can receive calls
on telephone sets connected to the Internet or Local
Area Network (LAN).

Background

It all started back in 1995 when Israeli computer
enthusiasts made the first computer to computer voice
connection. In the same year this technology was
developed into a software package called Internet Phone
Software. All that was needed to talk to another computer
user was a modem, sound card, speakers, and a microphone.

The software digitized and compressed the audio
signal before sending it over the Internet in data
packets. These voice connections could only occur between
computers which had the software installed. The sound
quality was very poor - nowhere near the quality of
standard telephone connections.

The technology continued to be developed and by 1998
gateways had been established to allow PC-to-phone
connections. Later that same year phone-to-phone
connections that used the Internet for voice transmission
were set in place. These phone-to-phone connections
still required a computer to initiate the call, but once the
connection was established, the callers could use a
regular phone set.

VoIP Today

There are currently many VoIP services available for
residential and commercial use. Some of these still
rely on PC-to-PC connections but may offer other services
such as PC-to-phone and phone-to-phone.

Internet phones are available that plug into the sound
card or USB port of a computer. These phones may have
number pads and ringers that allow you to use them the
same as traditional telephones. The computer can be
bypassed completely by connecting a phone directly to a
broadband modem (either DSL or cable).

How Does It Work?

The first step in using VoIP is converting your voice
into digital data. This is done by ’sampling’ your
voice - dividing the analog sound signal into discrete
steps that can be assigned a number value. Once your
voice is digitized, the data can be compressed.

This compressed digital data is split up into ‘packets’
of about 1500 bytes that can be transferred over the
Internet. As well as the voice data, the packets contain
information about their origin, their destination, and
a timestamp that allows them to be reconstructed in the
correct order. Once they arrive at their destination,
they are reassembled and converted from digital back
into analog so that the receiving party can hear your voice.

In order for voice data to be transmitted without
noticeable delays, a broadband Internet connection is
necessary. Many households and businesses are already
using broadband(either DSL or cable), so adding VoIP is
relatively simple.