By Suruchy Batta, Infosys Technologies Ltd.

Voice over Internet Protocol (VoIP) is a technology that allows you to make telephone calls using a broadband Internet connection instead of a regular (or analog) phone line. Some services using VoIP may only allow you to call other people using the same service, but others may allow you to call anyone who has a telephone number - including local, long distance, mobile, and international numbers. Also, while some services only work over your computer or a special VoIP phone, other services allow you to use a traditional phone through an adaptor.

VoIP converts the voice signal from your telephone into a digital signal that travels over the Internet then converts it back at the other end so you can speak to anyone with a regular phone number. When placing a VoIP call using a phone with an adapter, you'll hear a dial tone and dial just as you always have. VoIP may also allow you to make a call directly from a computer using a conventional telephone or a microphone.

Because the nature of VoIP is different than circuit switched networks, VoIP comes with a new set of issues. The most serious concern is Latency. Latency is the amount of time it takes between when you say something, and when it is heard on the other end. If the network is too slow or busy, and the packets don't arrive on time or in order, the conversation will fall apart. Studies show that people find latencies exceeding .25 seconds to be too frustrating to use. Because of this, quality of service (QoS) is an essential portion of a VoIP network, as it guarantees that packets will be delivered with minimal interruption.

A Simple Diagrammatic representation of the usage of VOIP

H.323 is one of the main protocol suites that facilitate the VOIP services. The following figure illustrates the structure of the key protocols in the H.323 architecture.

H.323 protocol suite

H.323 Protocol Suite Information Courtesy of Javvin Technologies (http://www.javvin.com)

For the full article of the “VOIP and H.323 Protocol Standard”, please click here.