Voice over IP By SAIKIRAN PANJALA

1. Voice over IPVoice over IP
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2. Contents
 Abstract
 Introduction
 What isVoIP
 HowVoIP works
 VoIP Architecture
 Components
 Conclusion
 References

3. Abstract
 With the aim of reducing communication costs, efforts of
integrating voice and data networks have been a rising
priority for many companies.
 Organisation have been working on the solutions which
would make the use the excess capacity on broadband
networks for voice and data transmission ,as well as
utilize internet and company intranet as alternatives to
expensive systems.
 At the same time more and more companies are seeing
the value of transporting voice over IP networks.

4. INTRODUCTION
 Voice over IP (VOIP), otherwise known as IP telephony, is the delivery of
voice information over Internet Protocol (IP) packet switched networks.
This means sending voice information in digital form in discrete packets
rather than in the traditional circuit-committed protocols of the public
switched telephone network (PSTN).A major advantage ofVOIP is that it
can avoid the tolls charged by ordinary telephone service by utilising fixed
charge IP network services such as broadband. Recent development with
SIP (see below) technology and hardware supporting this standard has
resulted in the production of a number of commercially marketed SIP
handsets, both wired and wireless networks, removing the need for a PC
or laptop running a software handset, or “softphone”, to connect toVOIP
services.A subscription to a local server from a SIP handset or softphone
provides you with all the normal telephony features including voice and fax,
as well as text and even video services.

5. What is VoIP?
 VoIP is packetisation and transport of
classic public switched telephone system
audio over an IP network.
 It allows 2-way voice transmission over
broadband connection.
 It is also called IP telephony, internet telephony, voice over
broadband, broadband telephony.

6. PSTN vs. INTERNET
PSTN
 Voice network use circuit
switching.
 Dedicated path between
calling and called party.
 Bandwidth reserved in
advance.
 Cost is based on distance
and time.
INTERNET
 Data network use packet
switching.
 No dedicated path between
sender and receiver.
 It acquires and releases
bandwidth, as it needed.
 Cost is not based on
distance and time.

7. PBX
Yesterday’s Networks
Circuit Switched Networks (Voice)
CO
PBX
CO
CO
Packet Switched Networks (Data)
Router
Router
Router
Router
Router
• Separated networks
• Separated applications/services

8. PBX
IP Phone
Converged Network
PSTN
CO
Gateway
Router
Router
Router
Router
• Converged network
• Separated or integrated applications
PBX
IP Phone

9. VoIP – How does it work?
 Converting the voice signal
 ADC (analog to digital)
 DAC (digital to analog)
Voice (source) - - ADC - - - Internet - - - DAC - -Voice (dest)
 Transmission of voice traffic in packets

10. VoIP – How does it work?
 The 1-2-3s of VoIP
 1. Compression – voice is compressed
typically with one of the following codecs, G7.11
64k, G7.29AB 8k, G723.1 6.3k
 2. Encapsulation – the digitized voice is
wrapped in an IP packet
 3. Routing – the voice packet is routed thru
the network to its final destination

11. LT
S©Telcordia Technologies, Inc. Slide 11
IP Network
Multimedia
PC
Multimedia
PC
Initially, PC to PC
voice calls over the
Internet
VoIP Architecture?
PSTN
(DC)
Gateway
PSTN
(NY)
Gateway
Public Switched
Telephone Network
Gateways allow PCs
to also reach phones
…or phones to reach
phones

12. Components
 VoIP Protocols
 VoIP Gateway
 VoIP Codecs

13. VoIP Network Model
SIP
RTP, RTCP, RTSP
Transport Layer (UDP, TCP)
Network Layer (IP, IP Multicast)
Data Link Layer
Physical Layer

14. PURC
IP Protocol LayeringIP Protocol Layering
Physical Transport (e.g, Cable Modem)
IP (Internet Protocol)
TCP UDP
Applications (e.g., email, web pages)
Email Data (1000 bytes)TCP Header
(20 bytes)
IP Header
(20 bytes)
A Typical IP Datagram

15. VoIP SIP

17. VoIP Gateway
 A VoIP gateway is a gateway device that uses Internet
Protocols to transmit and receive voice communications
(VoIP).

18. VoIP Codecs
 Codecs are used to convert an analog voice signal to
digitally encoded version. Codecs vary in the sound
quality, the bandwidth required, the computational
requirements, etc.

19. Do Companies Want VoIP?
76% Will!76% Will!
Unsure
4%
Not at all
likely
4%
Not very
likely
16%
Likely
28%
Very likely
32%
Extremely
likely
16%
Network World asked 500 readers to assess
whether they would consider using voice over IP:

20. Key Business Drivers for LAN-Based Telephony and VoIP
81%81%
59%59%
38%38%
26%26%
0 50 100
Save MoneySave Money
Better Utilization of BandwidthBetter Utilization of Bandwidth
Support MultimediaSupport Multimedia
Improve Network ManagementImprove Network Management

21.  AsVoIP uses the Internet, for example, it is vulnerable to
the same type as security risks
 Hacking
 Denial of service
 Eavesdropping
CONCLUSION

22. REFERENCES

23. THANKYOU