a seminar paper presentation .this will help you know about voice transmission over the internet protocol's.as in Skype, watts app. it also give an idea about old technology. thanks. if any mistakes ,and add any updates and share with me .on about this slide

1. VOICE OVER INTERNET PROTOCOL
(VOIP)
introduction
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2. VOICE OVER INTERNET PROTOCOL (VOIP) IS A
TRANSMISSION TECHNOLOGY FOR DELIVERY OF VOICE
COMMUNICATIONS OVER IP NETWORKS.
WHAT IS VOICE Vibration of substance produce sound.
in human beings it is done by vibration of vocal cord.
Sound in terms of electronics :The sound is the most
important way of communication in human beings. so in
electronics communication it is converted in to
equivalent electrical form by help of electronic
equipments.
 Distant Sound communication
 Evolution of analog & digital telephone network
 Internet telephony
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Dedicated line with a constant connection
Originally very expensive
Each call transmits at 64 kilobits per second
64 kbps x 2 directions = 128 kbps
128 kbps = 16 kilobytes per second
During a 10 minute call, about 10 MB
Highly inefficient

4. WIRED CONNECTION
 DP-Distribution point
 Cabinet
 MDF –Main distribution frame
 INTERNET TELEPHONEY
When the transport is the public Internet or the Internet
backbone from a major carrier, it is generally called
'Internet telephony’.
 VOIP
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5. HISTORY
• 1974 — The Institute of Electrical and Electronic
Engineers (IEEE) published a paper titled "A Protocol
for Packet Network Interconnection.
• 1981 — IPv4 is described in RFC 791.
• 1995 — Vocal Tec releases the first commercial
Internet phone software.
• 1996 — ITU-T begins development of standards for
the transmission and signaling of voice
communications over Internet Protocol networks with
the H.323 standard.
• 1999 — The Session Initiation Protocol (SIP)
specification RFC 2543 is released.
• 2004 — Commercial VoIP service providers proliferate
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6. STRUCTURE AND WORKING OF VOIP
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8. HOW VOIP WORKS?
VoIP protocols first converts your voice or
media into digital signal and travels over the
internet. At receiver side it decode in its original
format.
VoIP allows you to make a call from your
desktops/laptops or from IP phones using
internet. You can make a call from your
traditional telephones using spceial type of
phone adapter.
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1. PC to PC
• Need a pc with sound card
• IP telephony software
2. PC to phone
• Need a gateway that connects IP
network to phone network
( Router to PBX )

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(3) Phone to Phone
•Need more gateways that connect IP network to
phone network
•Ip network could be Internet or dedicated intranet

11. VOIP GATEWAY PROTOCOLS AND CODECS
 Codec ( coder – decoder ) :-
Software or hardware that converts analog signals to digital form
and signals from digital to analog form
 It also determines sound quality and bandwidth required to send the
packet
 If a user doesn’t able to hear anything, the application in user side
does not support codec with which data had been coded
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12. VOIP DEVICES
 ATA: Most useful device for VoIP is ATA(Analog
telephone Adaptor). It helps you to connect your standard
phone to computer and lets you call.
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13. NETWORK GATEWAY
 It is a network point that acts as an entrance to another
network
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P
B
X
IP Voice
IP
Network
PS
TN
VOIP
Gateway
Protocol
conversion
Voice
decompres
sion

14. PACKET SWITCHING VS. CIRCUIT SWITCHING
It is two different technologies for sending
messages and data from one point to another.
Each has its advantages and disadvantages
depending on what you are trying to do.
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15. CIRCUIT SWITCHING
 This channel remains open and in use throughout the
whole call and cannot be used by any other data or phone
calls.
 There are three phases in circuit switching:
Establish
Transfer
Disconnect
 The telephone message is sent all together; it is not broken
up.
 The message arrives in the same order that it was
originally sent.
 A circuit-switched network is excellent for data that needs
a constant link from end-to-end, for example, real-time
video.
 Circuit switching can be analog or digital.
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17. CIRCUIT SWITCHING
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Circuit is dedicated
to the call – no
interference, no
sharing
Guaranteed the full
bandwidth for the
duration of the call
Guaranteed quality
of service
 Inefficient – the equipment
may be unused for a lot of
the call; if no data is being
sent, the dedicated line
still remains open.
 It takes a relatively long
time to set up the circuit.
 During a crisis or disaster,
the network may become
unstable or unavailable.
 It was primarily developed
for voice traffic rather than
data traffic.
advantage Disadvantage

18. PACKET SWITCHING
 In packet-based networks, the message gets
broken into small data packets.
 These packets are sent out from the computer
and they travel around the network seeking out
the most efficient route to travel as circuits
become available.
 This does not necessarily mean that they seek
out the shortest route.
 Each packet may go a different route from the
others.
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19. PACKET SWITCHING
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20. PACKET SWITCHING
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 Each packet is sent with a ‘header
address’ which tells it where its final
destination is, so it knows where to go.
 The header address also describes the
sequence for reassembly at the
destination computer so that the packets
are put back into the correct order.
 One packet also contains details of how
many packets should be arriving so that
the recipient computer knows if one
packet has failed to turn up.
 If a packet fails to arrive, the recipient
computer sends a message back to the
computer which originally sent the data,
asking for the missing packet to be
resent.

21. PACKET SWITCHING
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 Security
 Bandwidth used to full
potential
 Devices of different speeds can
communicate
 Not affected by line failure
(redirects signal)
 Availability – no waiting for a
direct connection to become
available
 During a crisis or disaster,
when the public telephone
network might stop working, e-
mails and texts can still be sent
via packet switching
Under heavy use there can be
a delay
Data packets can get lost or
become corrupted
Protocols are needed for a
reliable transfer
Not so good for some types
data streams (e.g. real-time
video streams can lose
frames due to the way
packets arrive out of
sequence)
Advantage Disadvantage

22. IP - The Internet Protocol
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23. WHICH PROTOCOLS ARE REQUIRED FOR
VOIP………?
 UDP (User Datagram Protocol)
 RTP (Real-Time Transport Protocol)
 SIP( Session Initiation Protocol)
 H323
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24. UDP PROTOCOL
 Available in transport layer
 Enable the transmission of information between the
correct processes (or applications) on host
computers.
 UDP protocol is commonly used in transport layer
as an alternative to TCP protocol.
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INDUSTRY PROTOCOL STANDARDS
H.323 Protocol Suite

26. H323 ARCHITECTURE
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27. SIP PROTOCOL
 SIP is a application layer control simple signalling protocol
for VoIP implementations
 SIP: not only for VoIP, but in general for multimedia
communication
eg: audio / video conferencing, server-based or p2p
 provides the market with fast operation, flexibility, scalability
and multiservice support.
 format similar to HTTP
 creates, modifies and terminates sessions which are internet
multimedia conferences, Internet telephone calls and
multimedia
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28. SIP WORKS AS FOLLOWS
Callers and callees are identified by SIP
addresses
a caller first locates the appropriate server and
then sends a SIP request
a SIP request may be redirected or may trigger a
chain of new SIP requests by proxies
Users can register their location(s) with SIP
servers
SIP messages can be transmitted either over
TCP or UDP
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29. METHODS COMMAND:
- Invite: Initiate Call
- Ack: Confirm Final Response
-Bye: Terminate and Transfer Call
- Cancel: Cancel Searches and ‘Ringing’
-Options: Features Support by Other Side
- Register:Register with Location Service
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VoIP has become a powerful force in telecommunications due to several
reasons.
 cheaper than PSTN service providers
 compatible with web-based applications
 enabling the user to change, adjust , or listen to these
features
over the Internet.
 Long distance is usually provided free of charge.
Features
Call Waiting
Caller Id
Call Forwarding
Voice Mail
Call Transfer

31. VOIP PROVIDERS
Eg:
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Providers
Skype
Vonage
Speakeasy
Galaxy Voice
Packet 8

32. VOIP
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 Factors that Affect Call Quality in VoIP
Latency: Changing in delivery time
between voice packets
Jitter: Changing in delivery order of
voice packets
Packet Loss: Echo and jitter occurs
because of packet loss.
Echo: waving of voice
 Viruses, worms, and hackers
advantage disadvantage
Offer
Features
For Free
stuff
Saves Money And Cost
Efficient Integration With
Audio, Data
And Video
Applications
Ability To
Choose Your
Own Area
Codes
Flexibility

33. REFERENCES
 http://www.en.wikipedia.org/voip
 Data communications & Networking(4th edition-
BehrousA.forouzan)
 http:// www.iee.com
 Electronics for you vol.37
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