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VoIP Presented by: Adnan Sheikh Chris Howard Moises Uribe Cheri Kishida.

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Presentation on theme: "VoIP Presented by: Adnan Sheikh Chris Howard Moises Uribe Cheri Kishida."— Presentation transcript:

1 VoIP Presented by: Adnan Sheikh Chris Howard Moises Uribe Cheri Kishida

2 Overview  The History of this new technology.  What is Internet Telephony?  How does it work?  What are the Pros/Cons?  What are some of the companies that provide VoIP?

3 Objectives  To provide the class with an understanding of VoIP for personal/home use  To inform the class of the VoIP service providers available  To be able to leave this presentation knowing how to obtain and implement your own VoIP services

4 History  February 1995, first internet phone released by VocalTec, then other companies like Cisco & lucent entered the market  1996, Internet Telephone Consortium created (ITC) used as a means of discussing the technology, regulation policies, and market structure for the industry  Over time, Advancements in technology have made internet phone easy to use and an affordable service to use

5 What is Internet Telephony?  Technology using an Internet connection to pass voice data using IP instead of the standard public switched telephone network  Current: PSTN & POTS  Very flexible: supports PC to PC, PC to Phone, and Phone to Phone

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7 How it Works  Voice over internet protocol (VOIP) turns analog voice signals to digital data.  Lower costs – Domestic & International  Three types of internet telephony  ATA  IP Phones  PC to PC

8 ATA

9 ATA  Most common method  Analog Telephone Adaptor (ATA) is an analog to digital converter  Enables you to connect a standard phone to a computer or Internet connection

10 IP Phones

11  Similar to normal phones but have an RJ- 45 (Ethernet) connection instead of the standard RJ-11 connection  Contains all hardware and software  Connect directly to router  Offices configured with all IP phones are said to have an IP Private Branch Exchange (PBX) set up

12 Computer to Computer  Obtain free or very low-cost software from companies.  Sender & receiver need equipment.  Need the software, Internet connection (preferably high speed), microphone, speakers, and a sound card..  Lower cost once equipment is purchased

13 Standard Phone  Dial tone means you have connection to local office of telephone carrier  Dial the number and call is routed through the switch  Connection is made using several interconnected switches along the way  Receiving party answers the call and the connection opens the circuit  Once you hang up, the circuit is closed and all lines that were in use are free

14 VoIP: How it Works  VOIP involves packet switching, therefore a constant connection is not required  The sending computer splits the data up into packets, each packet containing an address on it so that network devices know where to send them  Within each packet is a payload. The payload is whatever is being transmitted.  The packets are then sent to a router which sends the packets to another router, and so on and so forth until they reach their destination.  The receiving computer then puts all of the packets back together again in the proper order using instructions contained within the packets. These instructions are necessary because the packets may take different paths and arrive in the wrong order.

15 VoIP: How it Works  VOIP uses the internets packet switching network  When you pick up the receiver it sends a signal to the ATA  The ATA receives the signal and sends back a dial tone  When you dial a number the tones are converted into a digital format and then momentarily stored.  The phone number you dialed is then sent in the form of a request to the VOIP companies call processor  The call processor then checks to see if the request is in a valid format.  The call processor then determines how best to map the call  The phone number is then translated into an IP address.  A device called a soft switch then connects the two devices, whatever they may be.  A signal is then sent to the now connected phone telling it to ring.  Once the phone is picked up a session is established.  As your conversation is going on packets are sent back and forth whenever there is data to be sent.  When the phone is hung up the circuit is closed and the ATA sends a signal to the soft switch terminating the session.

16 VoIP – Behind the Scenes  Protocols  Encoding  Achieving the quality

17 The Protocols  Various protocols include H.323, SIP, Skinny Client Control Protocol, Megaco (MGCP), MiNET, IAX, and others  Source and destination of telephone call must be equipped with compatible versions of the same protocol  Gatekeeper assists the VoIP phones in placing the call through such functions as Address Translation, Admission control and Bandwidth control  The higher the call quality, the greater the bandwidth requirement

18 The Encoding  Source and destination phones must agree on the encoder/decoder to use  Some ITU standards include:  G.711 – bandwidth requirement around 64kbps  G723.1 – bandwidth requirement around 5.3kbps  Source speaks into phone and voice is chopped into 30 millisecond slices, each slice representing a packet of data  Packet is given a number and time stamp, placed in a UDP packet, and sent to destination’s phone via Internet  When there is silence, packets are even smaller and are sent only one out of every 180 milliseconds

19 Achieving the Quality  Factors of consideration  Lost Packets  Latency - amount of time it takes for a data packet to move across a network connection  Jitter – variation in timing or time of arrival of data packets

20 Achieving the Quality: Lost Packets  Packet loss cannot totally be prevented due to internet congestion  Packet loss is acceptable if the lost packets are distributed evenly and whole words are not omitted

21 Achieving the Quality: Latency  Direct effect on speech quality  Delays less than 150 milliseconds can go undetected  Delays greater than 500 milliseconds are highly annoying  Indirect effect on speech quality  Echo – although this can be minimized through use of a headset

22 Achieving the Quality: Jitter  Sound packets do not arrive at destination’s phone at the exact timing they left the source’s phone.  Jitter is minimized when source and destination are on the same LAN  Digital buffer is used to ensure packets are received in the intended order

23 ATA Implementation

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29 VoIP Phone Example

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34 PC to PC  Very easy to start  A number of companies offer this service at little or no cost  PC to PC communication is usually offered free of cost to attract customers  Local, long distance, and international rates offered are much lower than traditional telecommunication company rates

35 Minimum Requirements  A Pentium processor based PC  Microsoft Windows 95 or newer operating system  A properly configured sound card  A pair of speakers and a microphone  A stable internet connection (at least 28.8 kbps)

36 Net2Phone.com OOOOne of the first companies to start internet telephony VVVVery easy to use: DDDDownload software CCCCreate user account SSSSelect amount of money to add to your account LLLLogin to the software YYYYou are ready to make PC to PC, PC to Phone, PC to FAX calls

37 Net2Phone.com OOOOffers free PC to PC communication service CCCCompetitive rates for international PC to Phone dialing

38 Hotfoon.com AAAA good service if calls are mainly made through Asia / Far East OOOOffers PC to Phone service only RRRRates: WWWWhole USA and Canada: 10c/min IIIIndia (All mobiles), some cities: 10c/min PPPPakistan - some cities at 10c/min BBBBangladesh - Dhaka: 10c/min SSSSaudi - Damman, Riyadh, Jeddah: 12c/min UUUU.A.E.: 12c/min

39 Advantages of VoIP  A fairly new technology, useful for long distance voice communication  A much cheaper, often free, method of communication  Relatively easy to use and install  Far superior to that of a regular phone, especially for international calls  You can choose your area code & can take your phone number wherever you go

40 Advantages of VoIP  Low infrastructure costs – once IP is installed, minimal telephony infrastructure maintenance is required  Extra features that ordinary phone companies don’t offer like having your voic being sent to your , and dialing numbers from outlook

41 Disadvantages of VoIP  The quality of VoIP is variable and degrades when there is internet congestion  Possible latency and data integrity problems  Need constant High-speed internet (DSL, Cable)  Dependent on Power and Internet  Inconsistent handling of outgoing calls from fax machines, satellite television receivers, conventional modems, or other devices dependent on voice-grade telephone lines

42 Disadvantages of VoIP  911 less effective. Need to register phone or may not be routed to nearest emergency dispatch center

43 Summary  Cheaper alternative to the conventional phone services  Easy to implement and maintain  VoIP will likely grow in terms of popularity but may not replace the standard phone services  Companies will come out with new communication services with extensive features at competitive prices

44 A look into the future  Companies will continue to come out offering new communications services  Services such as Teleconferencing, videoconferencing, and collaboration applications may soon be available as part of your integrated IP-based voice communications package  Services such as Teleconferencing, videoconferencing, and collaboration applications may soon be available as part of your integrated IP-based voice communications package

45 Glossary  Address translation: The process of converting external addresses into standardized network addresses and vice versa  Admission control: A QoS policy used to control the admission of network traffic from outside a given administrative domain  Bandwidth control: Setting the maximum capacity of data transfer capacity of a digital communications system that a service is allowed to use  Gatekeeper: a service which provides zone management in the VoIP environment  Internet Telephony: Technology using an Internet connection to pass voice data using IP instead of the standard public switched telephone network

46 Glossary  Jitter: - Variation in timing, or time of arrival, of received signals; an unwanted lack of perfection which can lead to bit areas  Latency: Latency is the amount of time it takes for a data packet (i.e., a unit of data) to move across a network connection  Payload: In a set of data, such as a data field, block, or stream, being processed or transported, the part that represents user information and user overhead information, and may include user-requested additional information, such as network management and accounting information

47 Glossary  PBX: Private Branch Exchange. A privately- owned telephone switch, often used in large corporations to provide inside telephone connectivity and access to the PSTN  Protocols: An agreed-upon format for transmitting data between two devices  UDP: A connection-less, unreliable, transport protocol which provides multiplexing and error detection for applications which require a low- cost protocol for one-shot transactions

48 Web References 99/ftp/voip_protocols/index.html 99/ftp/voip_protocols/index.html HOWTO.html HOWTO.html

49 Web References c=NetworkingPeerPublishing&r=http%3A %2F%2Fwww%2Eerlang%2Ecom%2Fprot ocols%2Ehtml c=NetworkingPeerPublishing&r=http%3A %2F%2Fwww%2Eerlang%2Ecom%2Fprot ocols%2Ehtml actical_guide.pdf actical_guide.pdf

50 Web References s/voip.pdf s/voip.pdf


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