Final Report Auto Saved)

MAHANAGAR TELEPHONE NIGAM Lttd..((MTNL)) MAHANAGAR TELEPHONE NIGAM L d MTNL
MTNL(Mahanagar Telephone Nigam Ltd.) was constituted in the year April,1986. Previously it was a government organisation under the department of Telecommunication. The basic of MTNL is to provide best and fault free telephone services to the subscribers so that they are satisfied with what they get. MTNL is fast emerging as a global giant in the telecom sector in its endeavour to provide world class telecom services, MTNL is equipping itself with the µstate-of-art¶ machines and acquiring the latest gadgets to achieve the target of office automation. MTNL is pioneering the introduction of information technology in the telecom-sector through human resource development, capacity building, computerization of consumer services like telephone directory, integrated computer networks, computer based scanning and signature recognition of subscribers, internet and customer service management etc. The perceived threat of the Y2K problem was addressed effectively on a war footing. In addition, the Information Technology Division of MTNL is constantly keeping at bay hackers and attacks from viruses such as the recent ³ I LOVE YOU ´ bug. For an organisation like MTNL, the customer support services like billing, Directory Enquiry, IVRS, FRS, commercial etc. are very important. It plays an important role in the implementation of these support services. Directory enquiry service is an essential customer care service being provided by telecommunication service provider, It helps the customers to find out the whereabouts of their associates. It comes to their rescue in times of emergencies. MTNL New Delhi is regularly updating telephone directory on CDROM. For national directory services also, MTNL was the first to integrate and start the service. Presently directory enquiry services system is being accused by nearly 250 cities of India.

HISTORICAL DEVELOPMENT OF DELHI TELEPHONES HISTORICAL DEVELOPMENT OF DELHI TELEPHONES
1911 : Establishment of Delhi Telephones system with manual exchange 1926 : 1972 : lines 1973 : Opening of first automatic exchange (Lothian Exchange) X-Bar (31) Janpath-1 exchange commissioned. Delhi telephone crosses 1 lac Opening of X-Bar (67) Chanakya Puri exchange.

1975 : X-Bar Janpath-IV (34) exchange commissioned. X- Bar Shahdara East (20) exchange commissioned. 1976 : Shakti Nagar (74) exchange commissioned. Idgah-II (52) X-Bar exchange inaugurated by Fakhuruddin Ali Ahmed, President of India, on 28.8.76 and presided over by Mr. S.D. Sharma (Minister of communications). Opening of Shahdara East (20) Extension-I, X-Bar exchange on 31.8.76. It was inaugurated by Mr. H.K.L. Bhagat (Minister of State for Works and Housing) and Mr. S.D. Sharma (Minister of communications). Opening of Hauz Khas (65) X-Bar exchange on 18.10.76

1991-92:Commissioning of gross switching capacity of 1,18,000 lines. Interactive graphics system (IGS) for computerization of outdoor network plant installed. I-NET services installed. 1992-93: 83,558 new telephone connections provided. Morning wake up call facility introduced free to all electronic exchange customers. Voice Mail Services introduced. 1993-94: Commissioning of gross switching capacity of 1,69,250 lines out of which 100500 lines of new technology. Waiting list under OYT & Special category made current in most areas. 1994-95: Record commission of gross switching capacity of 226000 lines. 1995-96 : Record commission of gross switching capacity 323200 lines. Automatic Changed Number Announcement Service 1951/1952 using Interactive Voice Response System (IVRS) introduced. Fault Repair Service of all major exchanges computerized. Multimedia center with video conferencing facility opened. 1996-97 : Commissioning of gross switching capacity of 241028 lines and provision of 203100 lines in one year which is an all-time high. The waiting list almost completed except few pockets. ISDN services introduced commercially. 1997 : Wireless in local loop (WILL) phone system introduced.

SERVICES BY MTNL SERVICES BY MTNL CUSTOMER SERVICE CENTER (CSC) The various service centers provided are as follows :  Area Customer Service Centers {Located at the headquarters of the Area General Manager}  Sub-Area Customer Service Centers {Located at the office of Dy.General Manager of the respective division}  Divisional Customer Service Centers {Located at the office of the Divisional Engineer(Outdoor)of the respective division}  Mobile Customer Service Centers

CUSTOMER SERVICE MANAGEMENT SYSTEM (CSMS)
A fully computerized single window facility for all telephone related work, covering from registration of new phones to billing services and fault repair services.

I. Computerized booking of complaint 198/2198 II. Helpline service III. Voice Mail Fault Repair Service(VMFRS)
DIRECTORY INFORMATION SERVICES

I. Computerized Directory Enquiry II. On-line Directory Information Service III. Directory Dial up Service IV. Directory service for I-NET Subscribers V. Know your billing cycle/bill date
VOLUNTARY DEPOSIT SCHEME(VDS)
Under this scheme, the customer may make an advance deposit to MTNL based on his average billing and this deposit will be adjusted in the future telephone bills.

INTELLIGENT NETWORK
Intelligent Network Service( IN-Service ) e.g. free phone, premium rate service, tele voting, virtual private network, universal access network and Virtual Calling Card or Account Calling Card.

 Virtual Calling Card
This service allows customers to make a call from any tone telephone in the networks of Delhi and Mumbai to any destination-local, national or international even if the telephone from where the call is made is without STD facility.

 Account Calling Card
This service also provides the same facility as VCC. As in the case of VCC, here also there is no need of a telephone connection.

HOTLINE
For instant connection to your most often called number this facility is quite useful. With this facility one can connect the phone to any one pre-determined number.

CALL FORWARDING/ CALL TRANSFER
With this facility, incoming calls can be forwarded to any other telephone number within the same local area by availing this facility.

TELEPHONE SERVICES  Voice
Plain old telephone services through distinguished Public Switched Telephone Network with variety of phones plus services and direct-in-dialing facility of PABXs connected to the PSTN.

 Dolphin ª
Cellular services provided by MTNL.

 Garuda
Wireless in Local loop (WLL) : Service offered are both in fixed mode as well as portable mode (mobile).

ISP (INTERNET SERVICE PROVIDER)
Various features of internet service provided are as follows :

I. Single access number II. Faster access III. Uninterrupted service IV. E-commerce V. Online telephone directory( www.mtnl.net.in|) VI. Hourly News update VII. Login package CDs available for 199/250/500 hours VIII. No registration charges
ATM SERVICES CUSTOMER CARE SERVICES

I. New telephone registration, bill payment and complaint registration through internet II. Smart Card for payphone III. Meditation Billing Customer Care in GSM Mobile IV. Data Ware Housing V. Call Center
VOICE MAIL SERVICES I-NET
Data Service through X.25 based Packet Switched Public Data Network is called I-NET.

ISDN
Integrated Service Digital Network (ISDN) to meet the requirements of customer for data, voice and video on one line, both in Basic Rate Access(64 kbps) and Primary Rate Access(2Mbps).

OTHER SERVICES OFFERED BY MTNL TO THE SUBSCRIBERS

I. Telax-operational on local and international level II. Leased Line III. Telephone directory of MTNL is available on CD-ROM as well as on the internet IV. Single window computerized customer service centers introduced to provide
solution to all telephone related matters V. Introduction of electronic bill clearence scheme : Bill presentment and online electronic bill payment of telephone bills by MTNL subscribers implemented for Delhi subscribers. VI. Call Waiting : 118 (Activation) VII. Abbreviation Dialing : 110+directory no.+xx VIII. Call Diversion : 114+Telephone no.(Activation) 115+ Telephone no. (Deactivation)

IX. Morning Alarm : 116 (Activation), 117 (Cancellation) X. Dynamic Lock : 123-abcd-abcd (Registration) XI. XII.
124-abcd-1 (Lock) 124-abcd-3 (Open) Absent Subscriber (Abs) Caller Line Identification, Hotline.

TELEPHONIC COMMUNICATION TELEPHONIC COMMUNICATION
Telephony is the branch of line communication which deals with the transmission of spoken message. Telephony is the most widely used and common for telecommunication. Speech from one subscriber is converted into electrical signals in the telephone instrument which are transmitted over wires to the telephone exchange for being conveyed to another subscriber¶s instrument where the electrical signals are converted back into sound energy. The telephone exchange serves the essential purpose of interconnecting different subscribers.

TELEPHONE
A Telephone is a device which transmits and receives speech at a distance. The conversion between two speakers across a distance is due to the sound waves carried by the intervening medium that is air these sound waves are generated by the human voice. When these waves exert pressure on the diaphragm of the human ear, he receives the speech, although the audio frequencies range from 16 to 20,000Hz , a human voice or a musical instrument does not always produce all these frequencies. On the other hand they generate much narrower band of frequencies.

TELEPHONE TRANSMITTER
It is a transducer converting sound energy into electrical energy. The type of transmitter most widely used in telephone hand-sets of today is the carbon granule transmitter. It consists of a carbon granule chamber within which there are two carbon electrodes F and M. One of them that is F is fixed and the other that is M is movable along the conical diaphragm D.

When the diaphragm moves to and fro due to the impinging sound waves, the pressure on the carbon granule varies. The electrical resistance offered by the carbon granule varies according to the pressure and the current in an external circuit having these carbon granules as variable will vary.

TELEPHONE RECEIVER
This does the reverse function of a transmitter. It is a transducer which converts electrical energy into sound energy. The coming voice frequency current passes through a coil producing magnetic flux in the magnetic path consisting the iron path of the permanent magnet, the pole pieces and the diaphragm.

SYSTEM FUNCTIONING
The function of the whole system (connection between subscriber and the exchange) is quite simple. Two or more telephone exchange can also communicate with each other by sing optical fibre cables(OFC), this method adopts in such a case when the subscribers communicate indirectly to the another exchange. Suppose an exchange have the capacity of five thousands subscriber but there is more than five thousand subscribers under that exchange so in that condition this exchange communicates with other one. Other many conditions are also used for communication links of exchanges which is not described here. Another essential component required for transmission and reception of speech of a system is the dial. The dial is used to send specific impulses over the subscriber line, when the subscriber lifts his hand-set, the dc loop between subscriber and the exchange is closed and steady current flows through the loop. The impulsing spring of the dial which is connected in series with the line breaks the loops as many times as the number is dialed. The two contacts doc1 and doc2 are called dial of normal contacts and close as soon as the finger plate of the dial is displaced from its normal position. When impulses are being sent by successive closing and opening of the impulsing spring s-1 contacts doc1 and doc2 are in closed position and the loop current flows through these contacts, the bell, the transmitter and the receiver all remaining shunted.

NETWORKS
Networks play an important role to run, connect and communicate between exchanges or subscribers. In the telephone departments, there are these networks as given below:

I. Cable Network II. Transmission Network III. Switching Network

SUBSCRIBER LINE CONFIGURATION

SUBSCRIBER LINE CONFIGURATION is divided into two parts :  Indoor Part It further consists of :

I. Telephone II. Distribution Point (D.P.) - 10/20 pair III. Cabinet
 Outdoor Part It further consists of :

I. Main Distribution Frame (MDF) II. Switch Room



FIBER OPTICS
‡ ‡ ‡ ‡ Transmitting communications signals over hair thin strands of glass or plastic Not a "new" technology Concept a century old Used commercially for last 25 years

FIBER HAS MORE CAPACITY
This single fiber can carry more communications than the giant copper cable!

FIBER OPTIC APPLICATIONS

‡

Fiber is already used in: -- 90% of all long distance telephony ± ± ± ‡ 50% of all local telephony Most LAN (computer network) backbones Many video surveillance links

Fiber is the least expensive, most reliable method for high speed and/or long distance communications While we already transmit signals at Gigabits per second speeds, we have only started to utilize the potential bandwidth of fiber

‡

OPTICAL FIBER CABLE

A thin glass strand designed for light transmission. A single hair-thin fiber is capable of transmitting trillions of bits per second. In addition to their huge transmission capacity, optical fibers offer many advantages over electricity and copper wire. Light pulses are not affected by random radiation in the environment, and their error rate is significantly lower. Fibers allow longer distances to be spanned before the signal has to be regenerated by expensive "repeaters." Fibers are more secure, because taps in the line can be detected, and lastly, fiber installation is streamlined due to their dramatically lower weight and smaller size compared to copper cables.

SPLICING OF OFC CABLE

There are two splicing technique:

1. FUSION SPLICING 2. MECHANICAL SPLICING

Fusion Splicing
1. Understand that fusion splicing is basically two or more optical fibers being permanently joined together by welding using an an electronic arc. If a poor spice is made, the fiber ends may not melt together properly and problems can arise. 2. Prepare the fiber by stripping the coatings, jackets and tubes, making sure that only bare fiber is left showing. You will want to clean all the fibers of any filling gel. A clean environment is REQUIRED for a good connection. 3. Cleave the fiber. A good cleaver is mandatory to obtain a successful splice. When fusing the fibers together, you can either align the fibers manually or automatic, depending on what type of machinery you have. Once you've obtained a proper alignment, an electrical arc is used to melt the fibers together creating a permanent weld of the two fiber ends.

4. Protect the fiber with heat shrink tubing, silicone get. This will keep the optical fiber safe from any outside elements it may encounter or future breakage.

FUSSION SPLICER

Mechanical Splicing
1. Understand that the basic difference between mechanical splicing and fusion splicing is you don't require a fusion splicer. It's also considered a quicker method and there is no heat involved. 2. Prepare the fiber by stripping all the protective coatings away. You will then want to cleave the fiber as in fusion, but precision is not as critical to the splice. The ends are then mechanically joined together by positioning them inside the mechanical splice unit. In this step a connector or an adhesive cover is used to join the splice together. 3. Protect the fiber with heat shrink tubing. As in fusion splicing, this will keep the optical fiber cable safe from the outside elements or breakage.

TIPS AND WARNING:

# Mechanical splicing costs more per splice, the initial investment will be much lower than fusion. # In fusion optical splicing, the initial investment in machine costs will be much higher, but the cost per splice is much lower than mechanical. # Mechanical is quicker and easier, but the alignments of the fibers are not as accurate as fusion. Whichever method you decide to use, make sure the person doing the splicing is trained in the operation they will be performing.

SWITCHING SYSTEMS SWITCHING SYSTEMS

There are many switching systems used such as :

         

MEC X BAR FETAX SPC ETB C-DOT OCB 283 CDMA EWSD 5ESS FETAX, SPC, ETB, OCB 283 are based on FRANCE technology. C-DOT is based on INDIAN technology. CDMA used in mobiles is based on CHINESE technology. EWSD is a SIEMENS make. 5ESS is an AT&T (Bell Lab. USA) make.

5ESS SWITCH 5ESS SWITCH
³5ESS´ stands for : 5 : 5th generation product as assigned by LUCENT TECHNOLOGY E : Electronic S : Switching S : System The 5ESS switch is a digital exchange that can serve as a local(lines), toll(trunks), tandem(lines and trunks) or international gateway exchange depending upon the type of switch. It can serve a small community with fewer than 100 subscribers or large metropolitan area more than 100,000 subscribers. The 5ESS switch is the most flexible digital exchange for use in the global switching network. It switches ISDN voice and data, local voice and long distance calls, internet access, wireless PCS, advanced intelligent network services, interactive video and multimedia services--- moving any kind of traffic(voice, data, video) on the public switched telephone network(PSTN). For service providers who need packet technology, the 7R/E Packet Driver converts your 5ESS Switch into a packet switch. The 5ESS Switch can transform your network into a multi-functional network, meeting your needs as well as those of your residential and business subscribers.

The 5ESS is a digital switching system with distributed processing. Distributed processing means that multiple processors handle all call processing functions

5ESS ACCESS TANDEM SWITCH
A high-capacity, high speed trunk switch that provides communication links between multiple regions and networks. It stores sufficient routing data to access a particular switch in another service provider¶s network and vice-versa. Eliminating the need for each end office to store routing information provides faster call transfer, results in administrative cost savings and gains access charge revenues. The Tandem Switch is a high capacity, high speed switch that connects geographically dispersed networks. Local end office switches are linked to each other via access tandem switches. Each access tandem switch aggregates voice and data calls from several local switches, then connects to a tandem switch in another area¶s network to move calls from one region to another. Typically, the tandem switch receives toll traffic and uses its trunks to process and route the traffic to and from another service provider¶s end office switch. Tandem switches have only trunks, not lines, which allow faster call transfer nationwide. This multi-use, flexible switch eliminates the need for each end office switch to store multitudes of routing information, provides faster call transfer and results in cost savings as well as gaining regulatory access charge revenues.

5ESS SWITCH HARDWARE
The 5ESS Switch hardware is subdivided into three major types of equipment modules with each of them involved in varying degrees in setting up and tearing down of every call :

 Switching Module (SM)
It connects the customer.

 Communication Module (CM)
It provides a path for control and data messages.

 Administrative Module (AM)
It collects the call completion data for engineering and billing. Each module performs the assigned functions that contribute to the total operation of the 4ESS switch. The SM connects all the lines and trunks to the 5ESS switch. It performs the call processing functions. There can be many SMs per 5ESS switch. The CM provides communication between SM and AM. There is one CM per 5ESS switch.

MODULAR DISTRIBUTED DESIGN

AM
DSCH

CM

SM

NCT links

NCT links

SM

SM

FEATURES OF 5ESS SWITCH  High Reliability
The 5ESS switch has the latest amount of downtime of any switch in its class, according to analysis of the latest U.S. FCC quality reports. The reports reveal that among four major switch vendors, the 5ESS switch is in four standard performance categories and set new in two key areas.

 Multiple Applications
The 5ESS switch is the only switch in the market today that can deliver any media of the same switch. The 5ESS can deploy all types and combinations of services from a single platform including wireline, wireless, voice and data. Together with the 7R/E Packet Driver, the 5ESS switch integrates IP/ATM networks and circuit switching. Therefore, service providers can offer the latest data services by building on their current switch investment.

 Modular Design
This feature distinguishes the 5ESS switch from all others because its intelligence is distributed into modules. This unique architecture allows growth in increments simply by adding modules, which can be dedicated to specific services, such as long distance and data services. Therefore, adding new services when and where the service provider needs them becomes quick and easy. Also, remote switch modules can be located upto 600 miles

from the host switch, making it easy to enter new categories. Basically, the switch supports any network strategy without locking the service provider into a specific future and without interrupting current services.

 Market Leadership
With an embedded base of more than 108 million lines and 48 million trunks served by 4000 host switches in more than 52 countries. The 5ESS switch product family includes a range of switches in varying sizes to meet diverse communication needs. The 5ESS switch is a market leader. A full-sized as the most reliable 5ESS switch serves upto 250,000 subscriber lines and over 100,000 trunk lines, with the flexibility to meet the most diverse business needs.

 5ESS Supports Wireless
The 5ESS switch continues Lucent Technology¶s leadership role in the wireless area providing advanced wireless services such as FDMA/TDMA/CDMA on the 5ESS Switch Very Compact Digital Exchange (VCDX). This low cost service application eliminates the ³pops and clicks´ of call hand-offs between cells over a large geographic areas. It improves billing for cellular customers to increase revenue and improve customer satisfaction and offers multiple grades of service to provide pricing flexibility for targeting different customers in the wireless market.

 5ESS Switch Configurations
Several switch configurations are available to serve differing networking functions and needs. The 5ESS switch innovative modular design assures network operators of complete flexibility in planning switch deployment and network growth.

BENEFITS OF 5ESS SWITCH

I. The only media switch in the market today providing wireless, wireline, voice and data
on a single platform. II. A high density switch, reducing floor space requirements and power consumption. III. A high capacity switch allowing fewer layers in the network providing network efficiency and reduced operational costs IV. #1 in reliability according to U.S. FCC Automatic Reporting Management and Information (ARMIS) Report V. Capable of evolving to the 7R/E Packet Solutions.

5ESS SWITCH APPLICATIONS

Current applications supported by the system are as follows : I. Local Exchange II. Toll Exchange III. Gateway Exchange IV. OSPS (Operator Service Position System) V. ISDN (Integrated Services Digital Network) VI. STP (Signaling Transfer Point) VII. SSP (Services Switching Point or Action Control Point) VIII. MSC (Mobile Switching Center or Wireless)
 Local Exchange
Local subscribers gain access to the local exchange through lines. The exchange switches a call from an internal subscriber to another subscriber directly or through a trunk circuit to a subscriber in another exchange. A trunk circuit (or trunk) connects a local exchange to a local exchange or a toll exchange. A local exchange has high percentage of lines and a small percentage of trunks.

 Toll Exchange
A Toll Exchange or Trunk tandem Exchange connects a local exchange to another local exchange or to a gateway exchange. A Toll exchange has high percentage of trunks but low percentage of lines, if any.

 Gateway Exchange
There is one international network consisting of interconnected gateway exchanges. Each country (A and B) in this network has its own gateway exchange, an international toll exchange. International calls enter or leave the country from this exchange.

C

C

1

2

 Operator Service Position System
The 5ESS-2000 offers automatic operator services via the OSPS. OSPS applications are directory enquiry to supply directory numbers to calling subscriber. Traffic Assistance allows operators to complete calls and respond to enquiries for subscriber. The OSPS uses a special SM called PSM (Position Switching Module).

 Integrated Service Digital Network
Another type of 5ESS-2000 switch application is the ISDN. It offers new voice and data services and allows features such as OSPS. It also allows voice, data and signaling information to travel over the same digital subscriber line. It lets all three components use the same transmission path simultaneously.

Two people with ISDN can make phone calls and use their computer terminals to access one or more computers at the same time. ISDN service is fully compatible with POTS service. ISDN service requires specific ISDN hardware and software in the SM.

 Signaling Transfer Point
The STP is an exchange application that sends signaling message on the way to the proper destination over a different path than voice circuit. TPs are associated with the CSS7 (common channel signaling 7) network. This application allows for more efficient use of trunk circuits.

 Service Switch Point
The SSP, also called ACP (action control panel) is a 5ESS-2000 switch application that is a part of IN (intelligent network) configuration. IN technology allows the introduction of advanced services, primarily through software updates, with minimal network rearrangements and minimal service disruption. The SSP is able to recognize the incoming IN calls, process them or request call handling instructions by use of a remote database that is accessed by many switches in the IN.

 Mobile Switching Center
The MSC (Mobile Switching Center) perform the switching function for wireless systems. This 5ESS-2000 switch application monitors subscriber mobility manages resources, communicates with other networks, performs call routing and control functions. The MSC configuration includes the AM, CM, SMs, WGSM (wireless global switching module), at least one WSM (wireless switching module) and possibly a WRSM (wireless remote switching module) or multimodule.

GROWTH AND DEGROWTH
Modular architecture makes it easy to increase or decrease the capacity of the exchange. Increase in the capacity of the switch is called growth. Decrease in the capacity of the switch is called degrowth. The SM is the primary module for growth and degrowth is accomplished by changing the number of SM in a switch or the number of units within the SM.

SWITCHING MODULE
The primary job of the switching module is to connect subscriber lines and inter-office trunks to the 5ESS switch. A switching module is a multi-unit component and is located in a variable number of cabinets. The switching modules are available in two models :

 SM configuration
Each SM contains a duplicated MCTSI, duplicated DLIs and two LDSU DSUs. All other hardware components are configured according to office requirements.

 SM-2000 configuration
Each SM-2000 contains a duplicated MCTSI, duplicated NLIs and LDSF DSCs. All other hardware components are configured according to office requirements which can handle more calls with less equipment. Switching Module(SM) is the most essential and vital part of a switching system. Originally SMs were called IMs (Interface Modules). With in a switch it performs the 90% of all the call processing functions as well as the circuit maintenance functions. The main function which constitute the process of call processing are :

I. Line scanning for tone originations II. Dial tone generation III. Digit collection and analysis IV. Call supervision
An SM terminates analog lines, analog trunks and digital trunks and lines. Within the switch architecture, SMs perform the time division switching functions. SM communicates with the AM for maintenance purpose or for obtaining routing information.

TYPES OF SM  LSM (Local Switching Module)
This type of SM serves local lines & ISDN users. The LSM is usually referred as SM.

 HSM (Host Switching Module)
This type of SM provides normal LSM subscriber interfaces and also one or more RSMs (Remote Switching Module).

 RSM (Remote Switching Module)
This type of SM is designed to meet the needs of those communities that are too small to be served by their own 5ESS switch in a remote area. This can be done by having the RSM connected to a HSM. This HSM can be far away as 242km. From host upto 4 RSMs, called a MMRSM (Multi mode RSM), can be interconnected to serve.

 PSM (Position Switching Module)
This type of SM supports OSPS features.

SM COMPONENTS

AIU CONTROL UNITS

LDSU

GDSU

SERVICE UNITS
MCTSI
SMP

TSI P DIU
TSI S U

DSU 2

TSI

TSI

TSI

HERE :

SMP ± It is used for processing the calls. TSI ± Time Slot Interchanger. LDSU ± Local Digital Service Unit. GDSU ± Global Digital Service Unit. PSU ± Packet Switch Unit.

SM can be broadly classified into two categories : SMC LTP The three main functional areas that exist in an SM are :

I. Interface Unit II. Control Unit III. Service Unit

SM INTERFACE UNITS
The interface units interface the telephone lines with the system. There are various types of interfaces needed to convert the telephone signaling systems into the format of the internal digit format needed by the exchange. Interface units exist for all the types of analog and digital lines and trunks, as well as for transmission systems between central offices. Every setup of a speech connection is started with detection in one of the interface units. Each interface unit has circuits that are developed for a particular type of signaling. After converting these signal into internal format of the exchange it transmits them to control unit which acts on them and make a connection from the interface unit to the service unit. In the service unit, tone detectors and tone generators are present. Detected tones are decoded and then the decoded value is transmitted to the control unit. Upon command from the control unit, call processing and signaling tones can be generated (by the LDSU) and transmitted to the interface units. In this way, the control unit receives the information for digit analysis and is able to respond according to the signaling type. There are various types of SM interface units which are as follows :

 Line Unit
It is the interface to the analog subscribers of various signaling types. The concentration ratio can vary from 4:1 to 10:1 depending on how the line units are equipped. The speech output per line is 64 time slots which enables a line unit to interface a maximum of 640 subscribers (10:1). A line unit is divided into two service groups, each processing 32 of the 64 time slots output by the line unit. It ensures that if an error has occurred in one service group then only maximum 32 calls within a line unit will be affected.



Integrated Service Line Unit-version 2 (ISLU2)
This interface unit is designed to meet the ITU-T requirements for an ISDN. It can interface with both analog as well as digital subscriber lines. The digital interface includes the U-DSL (digital subscriber lines). An ISLU2 can upto a maximum of 1024 analog and digital lines. A version of ISLU2 is RISLU2 (Remote ISLU) which may be located on the subscriber¶s premises when a large number of lines are to be interfaced from the same location. Since it is capable of performing line concentration, it can be used as pair gain system. It¶s an economical way for remote units.

 Analog Trunk Unit
It is an interface unit to the analog trunks. In this unit after conversion to the internal format of the exchange, the trunk traffic is transmitted to the control unit without any concentration factor. Since the trunk unit has 64 time slots available, every trunk unit can interfere with 64 analog trunks. These are grouped in pair of 32-32 trunks each. An error would affect a service group of trunks maximum.

 Digital Line Trunk Unit (DLU)
It is the interface unit to the digital trunks. A DLU is equipped with DFI (digital facility interface) circuits. With a 30 channel digital inter-exchange transmission facilities, each DFI can interface with a digital link carrying 30 data channels plus 2 signaling channels. In case of common channel signaling (CCS) DFI can interface with a digital transmission facility carrying 31 data channel and 1 signaling channel. Any combinations of interface unit may be installed as long as the capacity of standard control unit of SM200 is not exceeded. The signaling requirements of the interface units are handled under the control of the switching module control unit. All these interfaces support the signaling specifications from ITU-T.

SM CONTROL UNITS
The control units control the operation of the SM and perform the time switching of a speech sample. A speech sample can be switched either between two subscribers connected to the same switching module or between two subscribers on different SM2000¶s via the CM. The control units are fully duplicated in an active/standby configuration. Both of them receive the output signals of interface units, but the response of only active mode is acknowledged.

SM Control Unit & SMC Cabinet

A control unit is based on the following components:
 Module Controller Time Slot Interchanger (MCTSI)
This is made up of sub-components like Switching Module Processor Unit (SMPU), Time Slot Interchanger Unit (TSIU) etc.

The primary jobs of the SMPU are :

I. Controls call processing activities for the peripheral units in the switching module. II. Handles maintenance activities for the switching module. III. Monitors and reports all switching module activities to the AM to generate
hardware status reports IV. Handles subscriber data and control messages from the switching module peripherals and CM. V. Performs a ³bootstrapper function´ which enables the 5ESS switch to rapidly reload memory in the SMP.

 Network Link Interface (NLI)
The Network Link Interface (NLI) is a one paddle board component. The NLI is located in the backplane of the TSIU shelf in an SMC cabinet of an SM-2000. The main functions of NLI are :

I. Connect MCTSI to the Time Multiplexed Switch (TMS) part of CM. II. Convert subscriber data and control messages.
 Dual Link Interface
The Dual Link Interface (DLI) is a one circuit pack component. The DLI is located in the MCTU shelf of the SMC cabinet of a SM. The primary job of the DLI is to connect the MCTSI to the TMS.

Apart from the above main components of Control Unit, RSMs contain:

 Facility Interface Unit
It is located in shelf of RSM and contains components, the remote link interface. The primary jab of the RLI is to transmit subscriber data and control messages between a SM at a host site and a SM at a remote site. It also generates clock pulses for the RSM when the RSM is operating in a stand alone mode.

 Remote Clock Unit (RCLKU)
It has the following sub-parts :

I. RCLK Oscillator :
During a normal operation state, the RCLK oscillator provides a synchronizer with a source to remove jitter from the clock pulses that are received from the SM at the host site. During isolation from the host office the RCLK oscillator generates clock pulses for the RSM.

II.

RCLK Synchronizer : During a normal operation state the RCLK synchronizer removes jitter from the clock pulses.

SM SERVICE UNITS

Unit performs all tone detection and generation functions. Service Unit also provides test functions and call processing function such as three-party or six-party conferencing. It is composed of following sub-units :
Service

 Packet Switch Unit
The Packet Switch Unit Model 2 (PSU2) is a one to five shelf unit. The PSU2 is located in an LTP cabinet of a SM. The primary job of the PSU2 is to route packets of control messages & subscriber data to ISDN lines & C7 signaling trunks. The C7 signals are used to provide a path to set up and tear down trunk calls.

 Service Announcement System
It provides general recorder announcements like ³The following number has been changed´ or ³This number does not exists ´ and others.

 Global Digital Service Function
The Global Digital Service Function is a one circuit pack component. The GDSF is located in SMPU or DSU shelf of a SM-2000 cabinet, or CSU shelf of a SM cabinet. It receives and control message from MCTSI through PICB and tone generation and analysis through PIDB.

The primary job of the GDSF are :

I. Perform three and six port conference calling II. Perform transmission test III. Perform integrated system test IV. Generate an measure various tones to test
trunks

POTS and ISDN subscriber lines and

 Global Digital Service Unit
The Global Digital Service Unit is a multi-circuit pack component. The GDSU is located in a cabinet of SM. The primary jobs of the GDSU are to :

I. Perform three to six user conferencing II. Perform transmission tests on subscriber loops and trunks
 Local Digital Service Unit (LDSU)
It is one of the important parts of service unit which is connected through PICB to Control Interface (CI ) of MCTSI and through LDSUB to Data Interface (DI). Through PICB transmission of control messages occur to the SMP and through LDSUB tones are send and receive the TSI. The functions of LDSU are :

I. Generates call processing tones for digit and call progress alerts in an SM. II. Decodes call processing tones for routing calls in an SM.

CALL PROCESSING CALL PROCESSING

------------------------------------ 
Calling Subscriber Called Subscriber
Call handling is the processing of calls from calling subscribers to the called subscribers. In all exchanges the basic function is to process a call i.e. to assign a suitable path between the calling and called subscriber and thus ensure a faithful communication between the two. In 5ESS switch the 90% of call processing is done in SM Unit. A call processing may occur between following types of communications systems :

I. Public Switched Telephone Network (PSTN) : A tele-communication network set up by
an administration to perform telephonic services for public subscribers. The main characteristic of PSTN is that most PSTN subscribers have analog access to the network.

II.

Integrated Services Digital Network (ISDN) : A network which provides end-to-end digital connectivity to support a wide variety of services. Users of ISDN have access to a limited set of standard, multipurpose customer interfaces.

III. IV.

Global System for Mobile Communication (GSM) : A cellular network based on digital technology with international coverage for mobile telephony. Intelligent Network (IN) : A network that is organized in such a way that telephone calls, received by the IN are interrupted in query a database. The database has the capability to handle the call based on a number of predefined conditions. Personal Handy phone System (PHS) : A cellular network which offers low cost telephone service with low speed mobility.

V.

STAGES OF CALL PROCESSING FOR PSTN Digit Dialing Screening Index Digit Analysis Routing Charging Termination


Origination/Incoming

A call enters the exchange over a line (origination) or a trunk (incoming).
 Digit Collection
The collection of digits from the incoming line or trunk. Digit collection is responsible for :

I. Collecting dialed digits from incoming trunks or lines. II. Supporting the signaling protocol of the incoming trunk or line. III. Performing dial timing requirements.
 Digit Analysis
The digits collected by digit collection are analysed to determine routing. Digit analysis is responsible for :

I. Identification of the call type (normal call, dialed service, emergency number). II. Interdigit timing requirements (for example determine the minimum number
digits that are required to route the call). III. Generation of routing request data (for example destination index).

of

 Carrier Selection
Enables network subscribers to select the carrier used for a call. The carriers other than the access provider are called Other Licensed Operators (OLOs).

 Input and Output
The input for digit collection and digit analysis are the incoming digits. The output from the digit collection and digit analysis is for instance :

I. The Screening Index II. The Destination Index III. Charging Information
ROUTING
Routing is defined as the process of selecting the correct circuit path for a message. It translates the destination data received from digit analysis into the physical port that leads to the dialed destination (an outgoing trunk or line).

 Route
A possible trunk group (or multiple hunt group) leaving the exchange and leading to (but not necessarily connected to) the specified destination. The actual trunk (or line) must be found by ³hunting´ the group for an idle member.

Data associated with a route includes :

I. The trunk group (or multiple hunt group) member. II. The type of route (hunted, reorder, congestion, maintenance, etc.). III. Digit deleting and prefixing database. IV. The alternate (or next) route if the specified trunk group (or multiple hunt group) is
busy. Any route can be associated with one and only one trunk group. However the same trunk group can be busy by more than one route.

TERMINAL ALLOCATION
Terminal allocation is connecting the correct circuit path for a message to the incoming trunk or line.

 Route Index
An arbitrary number assigned by the telephone administration to uniquely identify one route out of the exchange. Route indices can also be assigned to specific announcements or tones.

 Alternate Route Index
It defines the next or alternate. An Alternate Route Index (ARI) can be used if the current route's trunk group (or multiple hunt group) is busy.

 Screening Index
An arbitrary number assigned by the telephone administration to uniquely identify the source of the originating line or incoming trunk call for routing and charging purposes. A screening index allows the same call type dialed to the same destination to be routed or charged differently, based on who originated the call. Screen Indices are obtained from line or trunk port data.

 Destination Index
An arbitrary number assigned by the telephone administration to uniquely identify each destination that can be reached for routing and charging purposes. Destination indices are obtained as an output of digit analysis. Types of terminations are : I. Line Termination (for the route types line and DSL) II. Multi-Line Hunt Termination III. Trunk Termination

CHARGING CHARGING
Charging is the function that assesses the cost of the usage of switching capacity and that passes on that assessment to the billing center. Currently two charging methods can be distinguished:

I. II.

Automatic Message Accounting (AMA) Multimetering (MM), also known as Periodic Pulse Metering (PPM).

In an exchange either method can be used or in combination.



AMA
Automatic Message Accounting (AMA) is a method of charging whereby for each call, records are generated for billing purposes. The records contain the information needed to generate a detailed subscriber bill, for example call start time, call end time, call duration, calling party number, called party number, and so on. Advantages :

I. II.

Allows detailed billing per call type or even per individual call Does not require tariff intelligence to be present in the exchange

Disadvantages :

I. II.

Requires large amounts of charging data to be collected and processed. Requires alternative methods to drive home meters and payphones.



MM

Multimetering (MM) is a method of charging whereby a call is charged in terms of charge units. The number of units to be charged is based on the distance (or route) of the call, the date and the time of day. All this information yields a charge rate which determines how many charge units are applied over a set time interval. Each time this interval expires during the call the calling party is charged the pre-determined number of units. Advantages :

I. II.

Only requires the number of imposed charge units to perform billing. Uses the charge units to generate meter pulses (to drive home meters and payphones or to transmit charging information to other exchanges).

Disadvantages :

I. II.

On accumulates charge units. No history is kept, so no detailed billing is possible.

What is charged?

I. II. III. IV. V. VI. VII. VIII.

Basic analog Public Switched Telephone Network (PSTN) calls. Basic digital Integrated Services Digital network (ISDN) Calls. Basic wireless calls (mobile originations and terminations), location updates and Home Location Register (HLR) interrogations. ISDN data packet calls. Subscriber programming actions for PSTN, ISDN and wireless supplementary services, for example activation, deactivation and interrogation. Exchange executable services like Alarm Call Service (ACS). The subscriber is charged when the service is executed by the system. All answered and unanswered calls that complete a Service Control Point (SCP) query, using the Intelligent Network (IN) PBX trunk originations.

Who is charged?

I. II. III.

Individual subscribers (PSTN and ISDN), mobile subscribers, individual PBX lines and PBXs Other administrations (to share revenues) Intelligent Network (IN) service providers.



Types of output

Normally the charging data is sent to a billing center. A billing center is a system, external to the exchange that performs the billing. The charging data is sent to the billing center using:

I. II.

Magnetic tape Direct data link to remote billing center.

MAINTENANCE TOOLS MAINTENANCE TOOLS

A maintenance staff responsible for maintaining a 5ESS switch uses the following maintenance tools :

I. Master Control Center (MCC) II. Trunk and Line Workstation (TLWS) III. Recent Change and Verify (RC/V) IV. Diagnostic Programs V. Documentation
 MCC
The MCC is the most important maintenance tool. Almost all the maintenance tasks can be performed from MCC. It uses a full-colour video display terminal as a window to the system. By entering poke commands selected from menus on the terminal screen or man machine language commands selected from the 5ESS-2000. Switch commands and report manual, maintenance personnel can diagnose equipment, remove equipment from service, restore equipment to service, test lines and trunks, modify the database and service features for customers. The ROP (Receive- only Printer) provides a printed copy of reports from the MCC.

The primary functions of the MCC are to provide the following :

I. Visual Display of the system status and alarm information. II. The means to control, test and reconfigure the system. III. The means to manually recover the system. IV. Access to exchange data.
 TLWS
It is a software function and is not related to a specific piece of equipment. As the name implies, the TLWS function is used to test trunks and lines (subscribers). Its functions can be performed from the MCC terminals known as supplementary TLWS positions.

 RC/V
It is also a software function. It is used to make addition, deletion , insertion, updation or changes to the database of the system. For instance, adding subscriber lines, changing the digit analysis, deleting trunks and so on are performed using the RC/V function. For example : update the subscriber class from Local to STD. Updb-sbldn : directory no. , SBclass=STD ;

 Diagnostics Programs
When a piece of equipment is faulty, the maintenance technician can run a specific diagnostic on that piece of equipment. The switch has the ability to tell the maintenance staff which circuit pack is most likely the faulty one and must be changed. The accuracy of the diagnostic process is quite impressive, more than 95% of system faults can be pinpointed, correctly. For example : for diagnostic of Line Ckt.² Dgn ± AIU : LC= xxxxxx-xx-xx ;

 Documentation
It plays a very important role in troubleshooting. Since a procedure may change over time, always refer to the documentation at the switch. Updating documentation must be performed whenever changes in new equipments are made.

FAULT DETECTING TOOL//TESTING TOOL FAULT DETECTING TOOL TESTING TOOL

OTDR Testing
OTDR (Optical Time Domain Reflectometer) technology is designed to provide a single ended test of any cable. Utilizing sophisticated algorithms, the equipment is able to calculate exact length and approximate loss of ³events´ along the cable span.

FEATURES:

1. Generates a baseline trace:
A ³visual´ of the link. 2. Can identify and evaluate specific events in the link. 3. Cable acceptance tool. 4. Fault location tool. 5. Excellent documentation capabilities. 6. Limited use in short length networks. <50ft

POWER METER
Power meter is a tool for measuring the loss on optical fiber cable .