VOIP is of a family of methodologies, communication protocols and transmission technologies for delivery of voice communication and multi-media sessions over internet protocol networks. The other terms used with VOIP are IP telephony, Internet telephony, voice over broadband (VOBB) broadband telephony and broadband phone.
The steps involved in originating a VOIP telephone call are signaling and media channel set up, as internet protocol packets over a packet switched network. On the receiving side, similar steps usually in the reverse order such as reception of the IP packets, decoding of the packets and digital- to-a long conversion reduce the original voice stream.
The technologies used to implement VOIP over protocol as under.
1. H 323 protocol found wide spread implementation for long-distance traffic, and local area services.
2. IMS: IP Multimedia Sub System.
3. MGCP: Media Gateway Control Protocol.
4. SIP: Session Initiation Protocol.
5. PGTP: Real Time Transport Protocol.
6. SDP: Session Description Protocol.
To connect to a VOIP service provider, a VOIP phone is necessary. VOIP phones connect directly to the IP network. You can also install a soft phone application Software on a networked computer that is equipped with a microphone and speakers, or headset. The application presents a dial pad and display field to the user to operate the applications by mouse clicks or key board input.
The VOIP is economical for large, medium as well as small enterprises. The services that treat all communication-phone calls, faxes, voicemail, e mail, web conferences and more-any means and to any hand set including cell phones. It allows voice and data communication run over a single network, which reduces the infrastructure costs and also the prices of extensions on VOIP are lower than for PBX and key systems.
A voice call originating in the VOIP environment faces challenges to reach its destination if the number is routed to a mobile phone number on a traditional mobile carrier. VOIP has identified as a least cost routing system, it is based on checking the destination of each telephone call as it is made, and then sending the call via the network that will cost the customer least.
VOIP services, that functions over managed networks are often considered to be available substitutes for PSTN telephone services, as a result, major operators that provide these services may find themselves bound by obligations of price control or accounting separation. But VOIP services that function over mismanaged networking are often considered to be too poor in quality to be a viable substitute for PSTN services, as a result they may be provided without any specific obligations.