IP_Telephony

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Under the guidance of [guide teacher name] Presented by your name:

Under the guidance of [guide teacher name] Presented by your name

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Introduction to IP Telephony Concept of IP Telephony Advantages Services in IP Telephony Ways of communication Network Architecture of H.323 Disadvantages Applications Future Equipment Conclusion Overview

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The current development on telecommunication industry is changing the use of telecommunication networks remarkably. People use telephone lines more and more for data transfer instead of ordinary voice calls. Obviously these changes has strong affection to the networks and operators.Public networks are moving from circuit switched networks to packet switched networks.This will cause telecommunication network and data communication networks which are mainly IP based . IP telephony means that voice and fax calls are transmitted over an IP network such as an Internet,rather than over the familiar PSTN. Introduction

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During last four years IP Telephony has become a hot topic.IP Telephony means transmission of voice over IP network. The basic steps for transmitting voice over IP network are:- 1.Audio from microphone are converted at audio I/p device. 2.The samples are copied in to the memory buffer in blocks of frame length. 3.Silence detector decides whether the block is to be treated as silence or as a part of a talks port. CONCEPT OF IP TELEPHONY

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4.if the block is talks port it is coded with a selected algorithm. 5.some header information is added to the block. 6.The packet is transferred over a physical network and received by the peer. 7.The header information is removed ,block of audio is decoded using the same algorithm it was encoded, and samples are written into a buffer. 8.The block of samples is copied from the buffer to the audio o/p device. 9.The audio o/p device D/A converts the samples and output them.

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The primary difference between the Internet and the PSTN is their switching architectures. The internet is dynamic routing(based on non-geographic addressing) versus the PSTN uses static switching(based on geographic addressing). PSTN dedicates a fixed amount of bandwidth for each conversation and thus quality is guaranteed. When a caller places IP Telephony call,she picks up the phone and hears a dial tone from the PBX if one is available.then she dials the number which is forwarded to the nearest IP Telephony gateway located between the PBX and TCP/IP network. IP Telephony Vs .PSTN

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Advantages of IP Telephony include lower cost long distance and reduced access charges,more efficient backbones and compelling new services. The benefits of shifting traditional voice onto packet networks can be reaped by businesses,Internet service Providers (ISP),traditional carriers etc. For consumers IP Telephony started from inexpensive or even free internet calls.Many households have only one telephone line which is often used of Web browsing. Therefore they would like to use IP telephony as a way of accepting incoming calls by rerouting them to PC. Advantages of IP Telephony

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There are three basic Services for IP Telephony: ATA -- The simplest and most common way is through the use of a device called an ATA (analog telephone adaptor). The ATA allows you to connect a standard phone to your computer or your Internet connection for use with VoIP. The ATA is an analog-to-digital converter. It takes the analog signal from your traditional phone and converts it into digital data for transmission over the Internet. IP Phones -- These specialized phones look just like normal phones with a handset, cradle and buttons. But instead of having the standard RJ-11 phone connectors, IP phones have an RJ-45 Ethernet connector. IP phones connect directly to your router and have all the hardware and software necessary Services in IP Telephony

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right onboard to handle the IP call. Wi-Fi phones allow subscribing callers to make VoIP calls from any Wi-Fi hot spot . Computer-to-computer -- This is certainly the easiest way to use VoIP. You don't even have to pay for long-distance calls. There are several companies offering free or very low-cost software that you can use for this type of VoIP. All you need is the software, a microphone , speakers , a sound card and an Internet connection, preferably a fast one like you would get through a cable or DSL modem . Except for your normal monthly ISP fee, there is usually no charge for computer-to-computer calls, no matter the distance.

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Communication using IP telephony is possible using four ways. These are as follows: Computer to Computer : This is a most convenient way of communicating while using IP telephony. 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 using the IP telephony, uses the software at the computer side, but the calls are charged with some minimal fees. Telephone to Computer : IP telephony communication in this way requires a special calling card at the telephone end and it Ways of Communication

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can communicate only with the computer that has a IP telephony 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 in IP telephony, uses the telephone on both the sides of the communication network. However, this way is least preferred by anybody using IP telephony, as the cost incurred is higher than the other mentioned ways of IP telephony .

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The network architecture consists of four types of network elements:Terminals,Gatekeepers, Gateways and Multipoint Control Unit(MCU). Network architecture of H.323

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Terminals:- these are clients which are able to receive or initiate calls.They generate and receive bi-directional real time information streams. Gatekeeper:- It manages a so called Zone ,which is a collection of terminals,gateways and MCU.Gatekeeper may also provide call control signaling,call authorization and call management. Gateways:- It is responsible for connecting IP telephone network to other type of networks,PSTN or ISDN. MCU:- Consist of multipoint controller and a number of Multipoint processors.The Mc handles control info and MPs handles the streams.

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The internet is an open network where everyone can receive and transmit packets relatively easily. Four basic security aspects are addressed in IP telephony:- Authentication: A process to ensure that the participants really are who they claim to be. Integrity: A process to ensure that the contents of the packet remains unchanged during transmission. Privacy:- Using ciphering mechanisms eavesdroppers are prevented to listen the contents of transmitted packets. Non-repudiation:- A process to prevent that someone can deny he or she done something. Disadvantages of IP Telephony Security issues

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IP telephony technology makes it easier to create new applications capabilities because it: carries and processes voice, data and multimedia traffic and signalling in the same form. And also utilizes the Internet Protocol and the host of open, standardized interfaces and software languages available to it. Examples of such capabilities and applications are: • IP Centrex – extends traditional Centrex capabilities to not only accommodate voice, but also data and multimedia; • Unified Messaging – delivers voice, fax and e-mail messages into a single mailbox that users can access Applications

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anywhere from a web browser, e-mail, or a telephone. Pre/Post-paid calling – offers a range of pre- and post-paid calling card capabilities created on an open platform. Internet call waiting – enables a single phone line for both voice calls and Internet access. Conference call capabilities. Call/Contact centres – enables a range of call centre capabilities, e.g. web enabled.

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Technology is developing very fast.In the future,there will be many diff kind of IP telephones popping out. The following list few properties that future IP Telephony terminals should have: Multi-functionality:-they can act like phones, pagers, credit cards ,notepad etc. Mobility:-they can be used to access wherever the user is. Design:-they must look and feel good. Price of the advanced equipment must be low. Future Equipment

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VOIP in its various forms raises several complex questions that go beyond the immediacy of whether or not consumers get cheaper telephone calls, but at the same time IP technology is ushering in a world of peer-to-peer communications that provides opportunities (and dangers) for multiple business models and players. IP telephony terminals can be entertainment center in the future. Radio and Video services could be used over IP network from home or even when the user is traveling by using mobile phones Conclusion

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