Internet protocol (VoIP) is the technology of digitizing sound, compressing it, breaking it up into data packets, and sending it over an IP network.The conventional technique used for sending voice is PSTN (public switched telephone network) . As data traffic has higher speed than telephone traffic, so what we do most of the time we prefer to send voice over data networks. Voice over internet protocol (VoIP) is a method of telephone communication over a data network.

1. PRESENTED BY:
Namra Afzal (1528)
Shahreen Gul (1544)
Rabiah Sharafat (1453)
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2. OUTLINE
INTRODUCTION
 WHAT IS VOIP?
HISTORY
PSTN Vs. VOIP
MODES OF OPERATION OF VOIP
BASIC PRINCIPLES OF VOIP
HOW VOIP WORKS?
ADVANTAGES
LIMITATIONS
APPLICATIONS
CONCLUSION
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3. INTRODUCTION
The traditional method used for transmitting
voice is PSTN.(public switched telephone
network)
Now more and more communication is done in
digital format and transported via data networks
such as internet.
 As data traffic is much faster than telephone
traffic, so we prefer to send voice over data
networks.
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4. WHAT IS VOIP?
 Voice Over Internet protocol (VoIP) is the
technology of digitizing sound, compressing
it, breaking it up into data packets, and
sending it over an IP network.
It is also called IP telephony, Internet
telephony, voice over broadband,
broadband telephony.
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5. VoIP Diagram
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6. HISTORY OF VOIP
•The commercial Voip software was
introduced in 1995 by Vocaltec.
Designed for home PC
Uses H.323 Protocol
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7. PSTN Vs. VoIP
PSTN
Refers to the international telephone system
• Telephone service carried by the PSTN is often called
(POTS).
• POTS (Analog Telephony)
It stands for Plain Old Telephone Service.
Dedicated link between partners
Reserved bandwidth
VoIP
Uses packet-switched telephony
 Voice info travels in countless individual
network packets
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8. Analog Telephony Digital Telephony
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9. PSTN vs. VoIP
PSTN
• Voice networks use circuit
switching.
• Dedicated path between
calling and Called party.
• Bandwidth is reserved in
advance.Each line is 64kbps
• Cost is based on distance
and time.
• Features such as call
waiting, Caller ID and so on
are usually available at an
extra cost
VoIP
• VoIP uses packet switching
• No dedicated path between
sender and receiver.
• It acquires and releases
bandwidth, as it is needed.
• Cost is not dependent on
time and distance.
• Features such as call
waiting, Caller ID and so on
are usually included free
with service 9

10. PSTN
• Can be upgraded or
expanded with new
equipment
• Long distance is usually
per minute or bundled
minute subscription
• Hardwired landline
phones (those without
an adapter) usually
remain active during
power outage
VoIP
• Upgrades usually
requires only
bandwidth and
software upgrades
• Long distance is often
included in regular
monthly price
• Lose power, lose
phone service without
power backup in place
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11. PSTN
• When placing an
emergency call it can be
traced to your location
VoIP
• Emergency calls cannot
always be traced to a
specific geographic
location
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12. CIRCUIT SWITCHING PACKET SWITCHING
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13. MODES OF OPERATION
•PC to PC
•PC to Phone
•Phone to Phone
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14. 14

15. 15

16. 16

17. 17

18. Basic Principles of VoIP
Audio Codecs,Video Codecs
Data Transport (RTP, RTCP)
 Addressing
 Signaling (SIP, H.323)
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19. Audio Codecs
 Are used to convert analog signal into digital data.
 The most common codecs for VoIP are
Codec Bandwidth/kbps
G.711 64
G.722 48/56/64
G.723.1 5.3/6.3
 Stands for coder-decoder
 Since voice contains lot of data, it is compressed by
coders without compromising the reliability and quality of
voice signal.
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20. Translation of analog signal to digital signal
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21. Video Codecs
• Video Codecs: common examples include
H.261 (for 64kbps and above), H.263 (for
64kbps and below), and MPEG 4.
• The encoded information is then
encapsulated within an IP packet and
these packets are then transported across
the network to their destination.
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22. Data Transport (RTP,RTCP)
RTP
•It stands for Realtime Transport
Protocol.
•Application layer protocol for
transmitting real time data (audio,
video, ...)
•Includes sequence numbering, time
stamping, delivery monitoring.
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23. RTCP
•It stands for Realtime Transport Control
Protocol.
•While RTP carries the media streams
(e.g., audio and video), RTCP is used to
monitor transmission statistics and
quality of service (QoS) and aids
synchronization of multiple streams.
•Main functions:
• support for multi-point communication
• Periodic transmission of packets to all
participants in the session.
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24. ADDRESSING
•Here phone no. is converted to an IP
address.
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25. VoIP SIGNALING PROTOCOLS
• Signaling in VOIP is needed for :
to establish a point to point
connection and to keep it open for
the duration of the call.
agreeing on coding / decoding
procedures.
• Types of Signaling Protocols:
o H.323
o SIP 25

26. H.323
•Recommendation published by ITU in
1996.
• It is designed to act above transport
layer and is mainly used for
transmission of voice, data and video
conferencing over packet networks.
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27. SIP
•SIP stands for Session Initiation Protocol.
•Developed by IETF since 1999.
•SIP is the core protocol for initiating,
managing and terminating
communication sessions (i.e audio &
video call) over the Internet
•These sessions may be text, voice, video
or a combination of these
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28. • SIP sessions involve one or more
participants and can use unicast or
multicast communication.
• Sessions include Internet Multimedia
conferences or Internet Telephone
calls.
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29. How VoIP Works?
• VoIP converts the voice signal from
your telephone into a digital signal
that can travel over the Internet.
• Depending on the type of VoIP
service, you can make a VoIP call from
a computer, a special VoIP phone, or a
traditional phone with or without an
adapter. 29

30. How VoIP Works?
30

31. 31

32. ADVANTAGES:
• Cheaper call rates
• Simplification
• High efficiency
• Calling person need not necessary to
receive call.
• Better Voice Quality Using Wideband Codecs
• Adding new features and applications over
time is easy.
• Integration of voice, data, fax, video is
possible.
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33. LIMITATIONS
 Packet Delay
Packet Loss (no guarantee of delivering packets)
Jitter (variable delay)
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34. APPLICATONS
Real time applications:
• Telephony ( two-way)
• Radio-TV Broadcast (one-way)
 Non-real time applications:
• Email
OTHERS:
•Integration of data, voice and fax
•Video telephony
•Enhanced teleconferencing 34

35. COMMERCIAL APPLICATIONS
1: VONAGE
• founded in January 2001
• about 130,000 customers
35

36. 2: AT&T
AT&T is rapidly evolving from
a company that handles
mostly long-distance voice
calls to a company that
provides data and voice
communications over any
distance.
3: INODE
4:TELEKOM AUSTRIA
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37. CONCLUSION
●Like everything else, as the technology changes so at
first only a few companies like Cisco and Lucent
offered VoIP services, but the large
telecommunications carriers – such as AT&T and
Sprint -- are catching on.
●VoIP is predominately used for personal instead of
enterprise-wide use.
●The availability of high-quality audio using wideband
codecs, video conferencing, and document sharing
enables more effective and pleasant communication.
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38. • ELECTRONICS FOR YOU(VOLUME-37)
• Voip Fundamentals By Jonathan Davidson
• www.bestneo.com
• www.google.com
• www.wikipedia.com
• www.howstuffworks.com
• www.cisco.com
• www.seminartopics.com
• www.quintum.com
• www.tech-faq.com
• http://www.sipnology.com/en/company/19-voip-born 38
REFERENCES:

39. • http://compnetworking.about.com/od/voipvoiceoverip/g/bld
ef_pstn.htm
• http://www.voip-facts.net/signalling-protocol-h-323/
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THANK YOU 