127559029 ip internet telephony

7/28/2019 127559029 IP Internet Telephony

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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

[email protected]

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

[email protected]

[email protected]

[email protected]


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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 ???????

127559029 ip internet telephony

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