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IP/INTERNETTELEPHONY
Presented By:
Information Science & Eng.
8th semester
Shree Devi Institute Of technology
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CONTENTS
1. What is IP Telephony
2. How IP Telephony works
3. Different types of IP Telephony
4. How IP Telephony is different over PSTN5. Different types of IP protocols
6. H.323 Components
7. Protocols Specified by H.323
8. Advantage of IP Telephony9. Disadvantages
10. Conclusion11. References
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What is IP Telephony:
IP telephony is point to point packet-switched network.
There are two main subsets.
a. Internet Telephony
b. Voice over IP (VoIP)
IP Telephony: Why ?
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How IP Telephony works:
Requirements :
Computer system or special IP phoneswith IP Telephony software.
Analog Telephony Adapters (ATA)
Broadband connection .
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IP Phones:
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Externalline
7043
7040
7041
7042PBX
Corporate/Campus
InternetLAN
8154
8151
8152
8153
PBX
Anothercampus
LAN
IP Telephony: PBX Replacement:
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Working of IP Telephony:
Analog Telephone Adaptor (ATA): Analog to digital converter
Internet Protocols
Packets
Gateway
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Features of IP Telephony:
Automatic use of network-based directories.
Conference calls.
Call transfer and hold.
Storing user name/number in systems facilitated by
different service providers. Weather report analysis.
Live news.
Voice Messaging Faxing, Fax Services, Fax Broadcast
Speech Recognition
Text to Speech
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Different Types Of IP Telephony:
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PC to PC:
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Phone to Phone Over IP:
There are two methods:
a.Phone-to-phone over IP usingGateways.
b. Phone-to-phone overIP using AdapterBoxes .
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Phone-to-phone overIPusing Gateways:
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Phone-to-phone over IPusing Adapter Boxes:
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- o- one or one-to-PC:
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How IP Telephony is different over PSTN:
Switching architectures.
Intelligence
Circuit switched network and Packetswitched network.
Comparable components of Internettelephony and the PSTN
Internet Telephony PSTNEnd system CPE & PBX
Gateway Signaling gateway
Signaling server SCP & SSP
Router STP
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Cont......
Comparable addressing concepts in Internet
telephony and the PSTN:
Internet Telephony PSTNMAC address Circuit identifier
IP address Routing number(E.164)
SIP URL, H.323 alias Telephone no,
including 800/900 no.
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Different type of IP telephony Protocols
H.323 standard
Session initiation protocol (SIP)
Media gateway to media controller protocol
(MGCP)Protocol Stack:
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What is H.323:
The H.323 standard for the transmission of real-
time audio, video, and data communications over
packet-based networks based on IP telephony.
H.323 is a standard produced by the ITU-T Study
Group 16.
Currently the most widely-supported IP telephony
signaling protocol.
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What is SIP:
SIP works in client/server relationships as well
as in peer-to-peer relationships.
SIP uses requests and responses .
Manual and automatic forwarding.
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Basic methods in SIP:
INVITE
OPTIONS REGISTER
CONNECTED
BYE
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SIP-based Voicemail Architecture:
INVITE
Alice
phone1.office.com
Bob
Alice calls [email protected] through SIP proxy.
SIP proxy forks the request to Bobs phone as well as to
a voicemail server.
vm.office.com
The voice mail server registers with the SIP proxy, sipd
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Voicemail Architecture:
v-mail
rtspd
Alice
vm.office.com;200 OK
200 OK
CANCEL
SETUP
RTP/RTCP
phone1.office.com;
Bob
After 10 seconds vm contacts the
RTSP server for recording.VM accepts the call.
Sipd cancels the other branch and ...
...accepts the call from Alice.
Now user message gets recorded
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H.323 Components:
Terminals
Gateways
Gatekeepers
Multipoint Control Units (MCUs)
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1.Terminals :H.323 terminal can either be a personal computer or a
stand-alone device.
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2.Gateways : A gateway connects two dissimilar networks.
Bridge between Internet and PSTN
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3. Gatekeepers:
Controller of an H.323 network
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Gatekeeper functions:
Address Translation
Admission Control
Bandwidth Control
Zone Management
Call-Control Signaling
Call Authorization
Call Management
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4. Multipoint Control Units:
MCUs provide support for conferences of
three or more H.323 terminals
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TheProtocols specified by H.323:
1. Audio CODECs
2. Video CODECs
3. H.225 registration, admission, and status (RAS)4. H .225 call signaling
a. Gatekeeper-Routed Call Signaling
b.Direct Call Signaling
5. H.245 control signaling6. Real-time transfer protocol (RTP)
7. Real-time control protocol (RTCP)
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Advantage of IP Telephony:
COST Saving
Reduced Initial Investment
Easy management Mobility
Improved Voice Quality
Software orientednature Packet switched network
Scalable
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Disadvantages:
Limited or no use in the absence of a dedicatedinternet access.
Total dependency on separate electricconnectivity.
IP telephony are easily get attacks from viruses
and hacking.
Exposure to Denial of Service attacks.
Much depends on the processor
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CONLUSION
IP telephony is cost savings and integratingnew services.
It is much cheaper than traditional longdistance services. Keeping this risingdemand of Internet telephony in mind, many
software companies have entered this field inorder to take a share of this growing marketsegment.
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Cont. The availability of free IP telephony software has
helped in increasing the market for IP Telephone
services, which is evident from the number of newusers that have subscribed to these services in recentyears. This holds good for the future of IP telephonyservices.
IP Telephony is a revolutionary technology that hasthe potential to completely rework the world's phonesystems.
In Future Integration with Web and long-termreplacement for current telephone systems
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REFERENCES[1] Book on IP Telephony Olivier Hersent, David Gurle &
Jean-Pierre Petit.
[2] www.iec.org/online/tutorials/
[3] www.cis.ohio-state.edu/~jain/cis788-97/internet_telephony/index.htm
[4] www.cs.columbia.edu/~coms6181/[5]www.terena.nl/library/IPTELEPHONYCOOKBOOK/chap
ters/Chapter4.pdf
[6] www.cisco.com/
[7] www.tmcnet.com/
[8]IP telephony client software
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THANK YOU ???????