VoIP - What it is, how it works and how it came about

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.

Overview of VoIP

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.