Era of VoIP technology ushered in 1995 by Israeli computer scientists in 1995, which succeeded in establishing the first computer to computer voice connection. All you have to do is that you have to install a soft ware onto your computer. The software digitizes and compresses the audio signal before sending it over the Internet in data packets. VoIP allows data and voice streaming within a particular network stretched all around the world. VoIP converts your voice into digital data by dividing the analog sound signals into separate steps that is assigned with different number value. This digital data is compressed and split up into packets of about 1500 bytes that can be transferred over the Internet. As well as the voice data, these packets hold information about their construction within accurate order, about their origin and their destination. At their destination, these packets are decompressed and converted from digital back into analog.

However, VoIP was originally developed to provide voice communication between computer users in different locations. Now, it has started to substitute existing telephone networks and some people and businesses are opting to VoIP instead of traditional phone line. You may have used this service unknowingly since many companies use VOIP to route long distance calls through a circuit switch into an IP phone, and another IP phone at the other end receives calls for another local circuit switch.
H.323 is an approval from the Telecommunications Sector of the International Telecommunication Union (ITU-T) it characterizes the protocols to provide audio-visual communication process on any network. H.323 was initially commenced to provide a method for transporting multimedia communication over local area network but later it evolved to address the growing requirements of VoIP networks. H.323 is now used in IP-based videoconferencing, VoIP, and Internet Telephony. Most VoIP phone systems involve endpoints, which give an edge to the extra usefulness of the VoIP. These endpoints act as-

H.323 data streams and signaling originate and cease in VoIP terminal either it may be in a multimedia PC with a H.323 recommendation or an IP telephone. This terminal support audio communication, along with video and data communication. A VoIP analog telephone adaptor compresses and decompresses the voice and carries voice communication between VoIP networks and traditional circuit-switched networks. A gatekeeper is a very useful routing and central manager of all endpoints within a VoIP network. A multipoint control unit can be used in both ways, integrated with a terminal, gateway, and gatekeeper or detached; it enables conferencing between two or more endpoints.