College Intercom Telephone System

A Real Time Project

CONTENTS

INTRODUCTIONTELEPHONE INTERNAL WORKINGABOUT INTERCOM SYSTEMPROTO TYPE OF TELI COMMUNICATIONMOTO OF THE PROJECTPROJECT LAY OUT PLANCABLES USEDEXCHANGE FEAUTERSPROGRAMMINGWORKING PROCEDUREADVANTAGESLIMITATIONSFUTURE SCOPE

GENERAL TELEPHONE SYSTEM

The circuit between the central office and customer is called the local loop. The local loop is the only remaining analog component in the system. Telephone calls are established by a device located at the local telephone companies Central Office (CO) known as a telephone switch. All voice traffic destined for locations outside of the local LATA must be handed off to the Long Distance or Inter-Exchange carrier (IXC) of the customer's choice .

INTRODUCTION

microphone receiver

Transmission system

Signaling and switching system

The analog system was the first telephone system established worldwide. Currently, telephone systems in countries are still completely analog. In time however, these systems will become redundant as the world switches to digital telephony.

The components of a telephone system include:

Microphone & Receiver

Transmission System

Switching and signaling system

TELEPHONE INTERNAL WORKING

Microphone, Receiver & Transmission System

Microphone

Converts the vibrations in the air into an electrical signal.

Receiver

Converts the received electrical signal into sound waves (the reverse action of a microphone) e.g.: loudspeaker.

Transmission system

Conveys the information representing the audio signal from the microphone to the receiver.

SWITCHING

The first telephone switch digitizes a voice call (8000 8-bit samples per second) Switching method is TDM.

Switch bundles multiple calls, by interleaving samples in time. Each call receives one 8-bit slot every 125 ms .

TelephoneSwitch

Sub-scriber

Sub-scriber

Sub-scriber

TelephoneSwitch

Sub-scriber

1-byte voice samples

Quiescent Offhook Dialing Wait

TalkingDisconnecting Ringing

Pick up phone

Dial Set up

Setu

p

com

plet

e

Put phone down

Remote

site picks up

Disconnect

SIGNALING SYSTEM

Signaling refers to the control functions performed to setup a phone call

Signaling between users and the local exchange in the central office is quite simple: dial-tone, punch numbers, put phone down etc.

RINGING CIRCUIT

The function of the ringing circuit is to provide the ring when the hook is off and also it has to provide the ringtone when hook is in on state The function of the ringing circuit is controlled by SLIC(subscriber line interface circuit). SLIC will send the ring pulse continuously to all the devices which are connected to the exchange by this function the user will come to know weather the device is in working state or not.

WHAT IS AN INTERCOM TELEPHONE SYSTEM??

intercom functions that enable paging and conversation between instruments of similar make and model. A single device can add intercom functionality to multiple standard telephones on a common phone line, even of different makes and models. Installation effort is minimal, and is not vulnerable to the radio interference and security issues of wireless systems.The intercom system we are using is an MATRIX SYSTEM.

MATRIX SYSTEM

Wired Matrix systems are systems in which a large number of individuals have the ability to establish private individual conversations from point A to point B.Depending on where in the English speaking world you are, you may refer to these types of systems as Matrix systems, cross point intercoms, point-to-point systems, private lines.Like the telephone system, matrix systems have other functions and capabilities. Conferences, call waiting, busy signals, and other features are common to many matrix intercoms.They are not limited to simple point-to-point communications. Some systems even allow inter-matrix routing of signals, similar to long distance telephones calls using trunks between central offices.

PROTO TYPE OF TELE COMMUNICATION

Attach one side of the red wire to one terminal of the power supply (Polarity does not matter). Take the 2-3 inches of wire and connect the other

power supply terminal to one end of the resistor. Attach the other side of the red wire to the

other end of the resistor. Attach the other side of the red wire to the other

end of the resistor. If everything is done correctly, one person on each end should now be able to communicate with each other.

MOTO OF THE PROJECT

The main Moto of our project is to provide fast communication between all the

departments.

PROJECT LAYOUT PLAN AND

T

E

L

E

P

H

O

N

E

S

TEST POINT

4 PAIR CABLE

1 PAIR CABLE

INTERCOM TELEPHONE EXCHANGE

BLOCK DIAGRAM

TestPoint

1

Test point

3

Test point

4

Test point

5

Test point

2

CABLES USED4-PAIR CABLE

SPECIFICATION Conductor Area CSA: 0.2mm² Conductor Material: Copper Coated Steel Current Rating: 0.25A Jacket Color: White No. of Cores: 8 Voltage Rating V AC: 80VUSAGE IN OUR PROJECT

The four pair cable is used to connect to establish connection from exchange to test points. By using this 4-p cable we can directly bring 4 devices connectivity at a point. And we can reduce the usage to cables.

1- PAIR CABLE

SPECIFICATIONProduct Type:CW1308 InternalNo. of Pairs/Cores: 1 PairCable Jacket Material: Low Smoke & FumeLength : 100mtColor : blackBrand: Homestead

USAGE IN OUR PROJECT The 1p cable is use to connect the telephone device from the test point. The wire was insulate with plastic and hence it is used for internal wiring so that there will be no distortion in voice.

CABLES USED

PINS USED

RJ11

RJ-11 (registered jack type 11) - the main usage of this connector was/is for stationary telephones, fax machines, modems. This connector was usually used as a standard in the 70's for telephone systems. A standard RJ-11 has 2 pins (2 cables) but I will show you a 6 pin one also. Besides that, a RJ-11 is very similar to a RJ-14 which has 4 pins. The main usage of this RJ's is for voice transfer. 

TEST POINTS

EXCHANGE FEAUTERS1) Making calls

2) Call pick –up

2.1)specific call pick-up

2.2)common call pick-up

3) Auto call back

4) CLI feature

5) Do not disturb

6) Barge-in

7) Monitoring

8) Conferencing

9) Call forward

10) Hotline

11) Alarms

12) Watch dog for watch man

13) Cable cut alarm

14) Emergency reporting

15) Last five called numbers & time display

16) Auto redial of last 5 called numbers

17) Voice

18) Display /printer mode

PROGRAMMING SECTION

AUTHORISATION

To prevent unauthorized users from reprogramming the system , a four-digit password has been set in the system.This password is kept confidential to prevent misuse of the system .

To reprogram any facility Dial main password *89 xxxx You shall get acceptance beeps Now you can program in required facility Once your programming is complete Dial 0

PROGRAMMING SECTION

NUMBER ALLOCATION

A) To allocate a number to a extension

Dial 37+XXXX+YYYYWhere XXXX= port number

001 for 2001 256 for 2256

YYYY= Any four digit numberExample: To set extension 2010 as 45,

Dial 37 + 010 + 45 #

PROGRAMMING SECTION

B) To wash all default extension numbers Dial main password 284+ABCD –DCBA

Where ABCD=main password DCBA= password in reverse order

CONFEREANCE CALL

When an extension is busy with some other extension to bring into conference,H/F &dial the third extension number

When third extension answers, H/F &Dial *0If more than one extension are to be added in conference go, on adding those extensions by

H/F and dialing the desired extension when all desired extensions have been added, announce conference and.

H/F & dial*0.

PROGRAMMING SECTION

PROGRAMMING SECTION

GROUPING:

FEATURE NAME FEATURE NUMBER

Internal dialing 00

Auto call back 01

Call pickup 02

Call forward/do not disturb 03

Hotline 04

Paging 05

Relay port access 06

Conferencing 07

Alarm 08

Barge in 09

Monitor 10

Feature no. 00 01 02 03 04 05 06 07 08 09 10

Group 0 N N N N N N N N N N N

Group 1 Y N N N N N N N N N N

Group 2 Y Y N N N N N N N N N

Group 3 Y Y Y N Y N N N Y N N

Group 4 Y Y Y Y Y N Y N Y N N

Group 5 Y Y Y Y Y Y Y N Y N N

Group 6 Y Y Y Y Y N N N Y N N

Group 7 Y Y Y Y Y N N Y Y N N

Group 8 Y Y Y Y Y Y Y Y Y Y N

Group 9 Y Y Y Y Y Y Y Y Y Y Y

Following 10 combinations of features are available

PROGRAMMING SECTION

WORKING PROCEDURE

When the user from one department wants to communicate with other

department’s by just dialing the department number he want to communicate.

And the other end user gets the ring from the telephone device and by lifting the

receiver he can attend the call.

INTERCOMTELEPHONEEXCHANGE

Test point-4

Test point-5

Test point-3

Test point-2

Test point-1

WORKING PROCEDURE

ADVANTAGES

Delay in communication will be reduced.

We can reduce the wastage of paper.

Human efforts can be reduced.

LIMITATIONS

This is limited to the specific location only.

FUTURE SCOPE

As we are using the devices based on the numbering but in future we can

implement by using the IP address.

The exchange was used to run 24 hours a day by using auto on/off we can

increase the life span of the device.