VOICE OVER INTERNET PROTOCOL
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VoIP (voice over IP - that is, voice delivered using the Internet Protocol) is a term used in IP telephony for a set of facilities for managing the delivery of voice information using the Internet Protocol (IP). In general, this means sending voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service
VoIP is therefore telephony using a packet based network instead of the PSTN (circuit switched).
During the early 90's the Internet was beginning its commercial spread. The Internet Protocol (IP), part of the TCP/IP suite (developed by the U.S. Department of Defense to link dissimilar computers across many kinds of data networks) seemed to have the necessary qualities to become the successor of the PSTN.
The first VoIP application was introduced in 1995 - an "Internet Phone". An Israeli company by the name of "Vocal Tec" was the one developing this application. The application was designed to run on a basic PC. The idea was to compress the voice signal and translate it into IP packets for transmission over the Internet. This "first generation" VoIP application suffered from delays (due to congestion), disconnection, and low quality.
Vocal Tec’s Internet phone was a significant breakthrough, although the application's many problems prevented it from becoming a popular product. Since this step IP telephony has developed rapidly. The most significant development is gateways that act as an interface between IP and PSTN networks.
What is Voice over IP?
Voice over IP (VoIP) is a blanket description for any service that delivers standard voice telephone services over Internet Protocol (IP). Computers to transfer data and files between computers normally use Internet protocol.
"Voice over IP is the technology of digitizing sound, compressing it, breaking it up into data packets, and sending it over an IP (internet protocol) network where it is reassembled, decompressed, and converted back into an analog wave form...” The transmission of sound over a packet switched network in this manner is an order of magnitude more efficient than the transmission of sound over a circuit switched network.
As mentioned before, VoIP saves bandwidth also by sending only the conversation data and not sending the silence periods. This is a considerable saving because generally only one person talks at a time while the other is listening. By removing the VoIP packets containing silence from the overall VoIP traffic we can reach up to 50% saving. In a circuit switched network, one call consumes the entire circuit. That circuit can only carry one call at a time.
In a packet switched network, digital data is chopped up into packets, sent across the network, and reassembled at the destination.
This type of circuit can accommodate many transmissions at the same time because each packet only takes up what bandwidth that is necessary.. Internet Telephony simply takes advantage of the efficiencies of packet switched networks.
Gateways are the key component required to facilitate IP Telephony.
A gateway is used to bridge the traditional circuit switched PSTN with the packet switched Internet.
The gateway allows the calls to transfer from one network to the other by converting the incoming signal into the type of signal required by the network it is required to send it on. For example, A PC user wishes to call someone using a conventional phone. The PC sends the IP packets containing digitized voice to the gateway.
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This post was written by: Rajendra Prasad
Rajendra Prasad is a professional blogger, web designer and front end web developer. Follow him on Facebook
