|Voice Over IP is a telephone service that uses the Internet as a global telephone network.
IP telephony is the two-way transmission of voice over a packet-switched IP network, which is part of the TCP/IP protocol suite. The terms "IP telephony" and "voice over IP" (VoIP) are synonymous. However, the term VoIP is widely used for the actual services offered, while IP telephony often refers to the technology behind it. In addition, IP telephony is an umbrella term for all real-time applications over IP, including voice over instant messaging (IM) and videoconferencing.
Globally, network transformation from circuit to Internet Protocol (IP)-based packet networks is taking place at a rapid pace. This transformation is enabling convergence of voice, data, and video networks to create and package services beyond the traditional services. The transformation is impacting all incumbent carriers of traditional voice services while bringing many new entrants into the market place. Packet switching is very efficient as it allows the network to route the packets along the least congested and least expensive lines.
Voice over Internet Protocol (VoIP) is a family of technologies that enable voice communications using IP networks Cost savings, user-slick telephony features, network convergence--VoIP is the technology at the root of all these trends.
VoIP technology comprises five major elements:
Media Gateway Controller (MGC): The MGC, often referred to as the softswitch, is responsible for call processing, service logic, routing, billing and other functions with the incorporation of SIP, SS7, SIGTRAN (M2UA, M2PA, M3UA, SUA), and MGCP protocols.
Media Gateway: Media Gateways provide switching and conversion of voice media paths between the PSTN and NGN/IP networks.
Signaling Gateway: Signaling Gateways are used to interconnect SIGTRAN-based signaling networks and SS7 networks. The Signaling Gateway performs signaling conversion both ways at the transport level between the SS7-based transport of signaling and SIGTRAN-IP based transport of signaling.
Application Server: Application servers are a key component of NextGen networks, and are an enabler of IP-based enhanced services. Examples include: all forms of conferencing, voice mail, and unified messaging. Because they are SIP based, application servers have the flexibility to easily offer services that go beyond the feature set of legacy switched telephony. In terms of network configuration, application server works in tandem with the media server, providing it with business logic and instructions for delivering enhanced services.
Media Server: Media Servers are a component of a VoIP (Voice Over IP) network and are controlled by Application Servers using SIP. The Media Server provides media processing functions, such as audio announcements, IVR (Interactive Voice Response), and multimedia conferencing.