How does IP Telephony Work
Telephony is the technology associated with the transmission of voice, electronically. IP telephony is a recent technological development that enables cheaper long-distance calls. The quality of the voice transmitted over IP is the same as that of the normal telephone calls. This technology uses the broadband Internet access for the transmission of voice over the Internet. The basic equipment required, is a broadband connection and a desktop computer or special IP phones.
IP - Internet protocol
IP telephony uses the Internet Protocol (IP) for transmission of voice, and also for communication through the packet-switched network of TCP/IP protocol suite. A protocol is a set of rules to be followed during any Internet communication. The Internet Protocol is a particular method of sending data and voice over the Internet, which works in conjunction with the Transmission Control Protocol (TCP) and thus, is known as TCP/IP.
In Internet Protocol, the information that is to be transmitted is divided into a number of chunks called packets. Each computer communicating has a particular IP address of its own. When the communication takes place, the packets of information contain the IP address of the sending and receiving computer. These packets are sent to the gateway computer. The gateway computer reads the receiver address on each of the packets. The gateway computer then sends the packets to their respective destination. The packets are sent in any order by the IP protocol. The Transmission Control Protocol ensures that these packets reach the destination computer in the correct order. The IP is a connectionless protocol and needs no specific physical medium for communication.
Types of Networks in IP Telephony
The IP telephony uses two types of public switched telephone network (PSTN). PSTN is a network of the voice oriented public telephones. PSTN provides much of the long distance infrastructure to the Internet as the Internet service providers use the PSTN for communicating over a long distance. The two types of PSTN networks used for the VoIP are access number and dial inward dialing. The extension number for contacting a person is required while using the access number network of PSTN. When using the direct inward dialing, no extension number is required.
Advantages
Cost: The cost of the IP telephony is very less, as it uses the existing network for communication. No new communication networks are required to be established for this technology. Also, the cost for setting up the packet switched networks is very less as compared to cost of the other networks. The cost further decreases, since the same network is used for transmitting voice and data. Many services like call forwarding, web conferencing and video calls, thus, are cheaper using this technology.
Mobility: This is a very convenient way of communication. Once you have an Internet connection and your computer, you can make a voice call anywhere in the world.
Ways of Communication
Communication using IP telephony is possible using four ways. These are as follows:
Computer to Computer: This is the most convenient way of communicating. This type of IP communication, is free of cost and distance is not a limit. The only cost incurred, are the Internet charges.
Computer to Telephone: This way of communication uses the software at the computer side, but the calls are charged with some minimal fees.
Telephone to Computer: This requires a special calling card at the telephone end and it can communicate only with the computer that has the required software installed. Although a calling card is required, it is far cheaper than the traditional way of making long-distance calls.
Telephone to Telephone: This way of communication uses the telephone on both the sides of the communication network. However, this way is least preferred, as the cost incurred is higher than the other mentioned ways.
IP telephony is a recent technological trend and is increasing rapidly because of the various advantages in household and business applications. It has revolutionized call rates and thereby, has led to the increased popularity of this technology as the most preferred way of making a voice call.
