Voice over IP (VoIP) is a blanket description for any service that delivers standard voice telephone services over Internet Protocol (IP). It is actually a system for transmitting telephone calls over data networks, such as the Internet.


Using either gateway devices or software applications on PCs, VoIP technology can allow users to talk to each other from PC to PC, PC to telephone, telephone to PC or telephone to telephone. Individual users and businesses can take advantage of the technology by using it to route voice data over their existing data networks, or by purchasing VoIP services from IP service providers.


Its use can result in huge savings in the amount of voice communication resources required to provide long distance voice communication. Moreover the infrastructure is already largely in place in the form of the many data networks that make up the Internet.


Voice over IP (VoIP) technology is growing rapidly, and it seems inevitable that this cheaper, more efficient technology will continue to play an important role in the world's telephone communications. It also means immediate cost savings and improvement in efficiency for businesses and individual users alike.

There are two major protocols used by VoIP technology to allow telephones, computers and other devices on the data network to communicate with each other.


The H.323 standard, a suite of protocols created by the International Telecommunications Union is a wide-ranging and very complicated protocol, providing specifications for a range of communication including video conferencing, data sharing and VoIP.


The Session Initiation Protocol (SIP) emerged after H.323 as an alternative, guided by the Internet Engineering Task Force. SIP is a much simpler, more streamlined protocol developed specifically for VoIP use, and designed to employ other protocols in handling parts of the communication process.