VoIP

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VoIP

• Presented by
• Adnan Sheikh
• Chris Howard
• Moises Uribe
• Cheri Kishida

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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?

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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

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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

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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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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

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ATA
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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

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IP Phones
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IP Phones

• 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

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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

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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

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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.

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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.

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VoIP Behind the Scenes

• Protocols
• Encoding
• Achieving the quality

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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

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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 destinations phone
  via Internet
• When there is silence, packets are even smaller
  and are sent only one out of every 180
  milliseconds

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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

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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

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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

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Achieving the Quality Jitter

• Sound packets do not arrive at destinations
  phone at the exact timing they left the sources
  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

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ATA Implementation
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ATA Implementation
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ATA Implementation
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ATA Implementation
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ATA Implementation
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ATA Implementation
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VoIP Phone Example
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VoIP Phone Example
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VoIP Phone Example
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VoIP Phone Example
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VoIP Phone Example
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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

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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)

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Net2Phone.com

• One of the first companies to start internet
  telephony
• Very easy to use
• Download software
• Create user account
• Select amount of money to add to your account
• Login to the software
• You are ready to make PC to PC, PC to Phone, PC
  to FAX calls

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Net2Phone.com

• Offers free PC to PC communication service
• Competitive rates for international PC to Phone
  dialing

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Hotfoon.com

• A good service if calls are mainly made through
  Asia / Far East
• Offers PC to Phone service only
• Rates
• Whole USA and Canada 10c/min
• India (All mobiles), some cities 10c/min
• Pakistan - some cities at 10c/min
• Bangladesh - Dhaka 10c/min
• Saudi - Damman, Riyadh, Jeddah 12c/min
• U.A.E. 12c/min

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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

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Advantages of VoIP

• Low infrastructure costs once IP is installed,
  minimal telephony infrastructure maintenance is
  required
• Extra features that ordinary phone companies
  dont offer like having your voicemail being sent
  to your email, and dialing numbers from outlook

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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

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Disadvantages of VoIP

• 911 less effective. Need to register phone or may
  not be routed to nearest emergency dispatch center

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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

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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

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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

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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

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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

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Web References

• http//en.wikipedia.org/wiki/Voice_over_IP
• http//www.cse.ohio-state.edu/jain/cis788-99/ftp/
  voip_protocols/index.html
• http//en.wikipedia.org/wiki/Voice_over_IP
• http//www.tldp.org/HOWTO/VoIP-HOWTO.html
• http//www.wilco-telephony.co.uk/voip.html
• http//www.jiwire.com/voip-guide-intro.htm

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Web References

• http//networking.ittoolbox.com/browse.asp?cNetwo
  rkingPeerPublishingrhttp3A2F2Fwww2Eerlang2E
  com2Fprotocols2Ehtml
• http//www.protocols.com/papers/pdf/voip_practical
  _guide.pdf
• http//www.net2phone.com/

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Web References

• http//www.dti.gov.uk/bestpractice/assets/voip.pdf
  
• http//vonage.com/
• http//hotfoon.com/