An apparatus to provide audio-visual communications across Local Area Networks (LAN) had been successfully handled by H.323 at a time when a broader arena in the transportation of multimedia applications was beginning to develop. The success of H.323 was acknowledged by the International Telecommunications Union (ITU-T ) when H.323 was introduced to meet increasing demands being created by the development and increased use of VoIP. In addition to its ready availability H.323 also provided supplementary services required to resolve future commercial communication activities. H.323 was the first VoIP standard to adopt the Internet Engineering Task Force (IETF) standard Real Time Protocol (RTP) to send audio and video over IP networks.

Signaling used in Public Switched Telephone Networks (PSTN) calls relate to the telephony signals which circulate the globe irrespective of international boundaries. In order that telephone services providers are able to communicate at an international level it has been necessary for their engineers to interact with those in other countries. Appreciating what an engineer operating in a foreign country is talking about may not be immediately obvious and because advances in technology were looming closer on the horizon in 1975 AT&T began to define what have developed into standard protocols that could be recognized at an international level. Even so the references adopted are not always immediately recognizable to anyone who operates outside the engineering environment for example in the United States SS7 is referred to as CCS7 and in the UK C7 (CCITT number 7).

STUN stands for Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs). STUN operates together with several other systems that achieve NAT traversal including: TURN, ICE UpnP and Session Border controllers. The efforts these systems seek to allow relate to withdrawing the limitations a client needs to experience in order to investigate its environment, although by doing so the environment complexity is significantly increased.

The Signaling System 7 (SS7) network was designed as a management tool to automatically organize call routing by assessing at a fraction of the time it would take to achieve manually the most appropriate direction in which a call should be sent with the support of all telephony services including 800 numbers, call forwarding, caller ID and local number portability. The SS7 Protocol was adopted as a standard by ITU-T in 1981 in its ITU-T Q7XX-series.

H.323 is the result of an International Telecommunications Union (ITU) specification for computers, equipment and services concerned with multimedia communications over networks that fail to offer a guaranteed quality of service. H.323 allows for the transmission of real time video, audio and data and has been specifically designed to provide the protocols that need to be observed in order to make available audio-visual communications on any packet network. In addition the H.32x series of Protocols encapsulate H.323 in order to provide services over ISDN, PSTN or SS7. H.323 provides a similar function to that of the Session Initiation Protocol when used in Voice Over Internet Protocol (V0IP), Internet telephony or IP Telephony. Early availability of H.323 provided a ready made set of standards that not only detailed the basic call model it also addressed issues relating to business communications expectations.

The modern communications have really evolved. Nowadays, people connect with their peers in other parts of the world through the Internet, which provide for faster and cheaper connection. Yes, because the Internet can facilitate for higher rate of connection, real-time interaction and cheaper costs, it is becoming a more popular venue where people can make calls, just like the way they used to do using land and mobile telephones.

The H.323 is a computer application standard that sets a foundation for data, video and audio communications throughout Internet-protocol based networks. The term is a jargon in modern information technology industry and only a few people have the full extensive and comprehensive knowledge and awareness of it.
The H.323 is defined by online site Webopedia.com as a computer application standard that sets specification for equipment, computers and services for communicating multimedia information and data over networks transmitted across the Internet.

Computer telephony has increased over the years. Technology has allowed the computer and telephone to share data more conveniently and with good quality. Because of the integration of contact channels like email, fax, voice and web service with computer systems, computer telephony has expanded.

With different types of external equipment appearing in the market to accommodate people’s communications needs, VoIP telephony was born. Voice over Internet protocol or VOIP telephony is today’s most popular service that allows users to make and terminate calls over the Internet to landline units. Apart from lower costs, voip telephony offers the same quality service as the traditional landline calls.

The telecommunication network that has helped to overcome the hurdles of distance for communication is the Signaling System No. 7 (SS7). Some of the ways in which SS7 is used in the communication network are the setting up of phone calls, providing cellular roaming and messaging, supplying congregated voice and data services. The evolution of SS7 and its advantages necessitates an in-depth understanding of the Protocol, Architecture and the Services of SS7.

In recent years, the internet technology has grown in leaps and bounds. One major product of this technology is the Voice over Internet protocol (VoIP). VoIP is a technology that enables better audio and visual communication from our home computers. Through this, we can communicate easily from wherever we are and it is cheaper than the conventional telephone services. The upfront investment required for this is also very less. VOIP is still in its early stages and it has to undergo more development before it can substitute the regular telephone.The two types of VOIP protocols used today are:
1. H.323
2. SIP