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Telecommunication II

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ISDN What is ISDN? What is an ISDN telephone? What is an ISDN line? Did U ever use ISDN connection? How to get an ISDN connection? Which equipment is required? How much it costs?

History of ISDN

Analog Telephone • The early phone network consisted of a pure

analog system that connected telephone users directly by an interconnection of wires. This system was very inefficient, very prone to breakdown and noise, and did not lend itself easily to long-distance connections

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Old System

Using modem over a POTS (plain old telephone system) to connect to Internet through ISP:

The home dialup modem converts digital signal from computer to analog signal.

A modem in the ISP converts the signal back to digital form for input to ISP router.

Data transmission is limited to 56kbps.

Analog and Digital Services

Integrated Digital Network

Integrated Services Digital Network

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ISDN ISDN Network Connection

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ISDN ISDN reference points/ Interfaces

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ISDN Integrated Services Digital Network Introduction ISDN brings the digital network to the

individual user Three separate channels at the same time,

through the same line Two of these channels (the B channels) carry

user "conversations" from a telephone, a computer, a fax or almost any other device. The third channel (the D channel) carries call set-up information for the network, but can also carry user data transmissions

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ISDN All information is transmitted in digital form

from end to end With the help of some hardware and

software updating, modern digital telephone exchanges are able to provide ISDN service

The ordinary two-wire subscriber loop of the telephone network is upgraded to the basic rate access of ISDN by an NT on the subscriber premises and by a basic rate interface unit and ISDN software in the local exchange

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ISDN User data contain two independent 64-Kbps

circuit switched user channels, B channels, and a 16-Kbps signaling channel, the D channel

Subscribers may use both B channels independently at the same time and dial them up independently, for example, using one of these channels for a telephone call and another for an Internet connection

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ISDN For Internet surfing B channels can be

combined to provide a single 128-Kbps data rate connection

ISDN provides a reliable 64/128-Kbps connection end to end, which is much more than that available for subscribers using a voice-band modem over an ordinary analog telephone circuit

The advantages of ISDN over the analog telephone service are a higher data rate and the availability of two connections at the same time

ISDN connections sometimes at a lower cost than two conventional analog telephone connections

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ISDN Existing telephone can be connected to an

analog port on the TA Telephones connected to the TA can be

used internally To drive its convenience features, it

wouldn't work in the event of power failure If I connect both my fax machine and

telephone to the TA, will they both ring when a call comes in, and is it possible for the TA to detect the type of call and route it to the appropriate device?

About additional telephone numbers

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ISDN An ISDN telephone Integrated Services Digital Network (ISDN) you may get one phone number per ISDN line

or one phone number for each ISDN B-channel Several TAs can be connected to a single ISDN

line An external TA or an ISDN card Caller ID, Transfer, Conference, 30-Number

Speed Calling, Call Hold, Call Pickup, and Call Forwarding at no additional charge. Voice Mail is available at no cost, and ISDN provides a visual message-waiting light on each ISDN set

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ISDN Terminal Equipment Any end-user equipment connected to an ISDN line through an

NT device is called terminal equipment. There are two classes of terminal equipment in the ISDN world. They are ISDN-ready (or digital devices) and non-ISDN ready (or existing analog devices such as telephones, fax machines, and data modems).

TA TA, Terminal Adapter, allows analog voice and data devices to

work through an ISDN connection. TA can be standalone equipment, but more often it is a port of an NT1 or TE1.

TE1 TE1 refers to the ISDN device that supports the standard

ISDN interface. It can be a digital phone, digital fax, or any other device that connects without an adapter.

TE2 TE2 includes any device that is non-ISDN ready, such as all

existing analog equipment. It cannot be connected to the ISDN line directly and requires a terminal adapter

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ISDN Network Termination Devices

Network termination devices serve as a demarcation point between telephone company and customer premises equipment.

NT1 The NT1 is a two- to four-wire interface. It

provides termination for the ISDN connection and supplies power to the ISDN line and non-powered ISDN devices

NT2 The NT2 device is an intelligent device that

supports higher-level functionality. It can perform switching and concentration functions. Examples of NT2 are a digital PBX, a terminal controller, and a LAN

ISDN (continued) Two types of services provided

through narrowband ISDN:1. The basic rate interface

(BRI):• is made of two B channels and 1 D

channel, suitable for small businesses and residential.

2.The primary rate interface (PRI):• is made of either 23 B channels or

30 B channels and one D channel, is suitable for businesses with digital PBX or LAN.

ISDN (continued)

The primary rate interface (PRI):

• 23 B channels at 64kbps each and one D channel at 64 kbps– Data rate=1.544 Mbps

» (used in USA, Canada, and Japan)

• 30 B channels at 64kbps each and one D channel at 64 kbps– Data rate=2.048 Mbps

» (used in Europe)

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ISDN ISDN services BRI/PRI

Figure 15-13

WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998

BRI Interfaces

Figure 15-17

WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998

BRI Frame

Figure 15-19

WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998

PRI Interfaces

Figure 15-20

WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998

PRI Frame

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ISDN ISDN network

components

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ISDN ISDN TA

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ISDN ISDN NT1

Advantages of ISDN Multiple Numbers

For single digital source, we can program upto 64 different numbers.

Multiple Services ISDN is using packet switching technique,

So at the same point of time we can utilize more than one service.

Out-of-Band Signal The Digital packet having the information

like who is calling, what type of call is it (data/voice), and what number was dialed. Using this information we can do the intelligent call handling.

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