REGIONAL TELECOM TRAINING CENTRE

LUCKNOW

Summer Training Programme

OVERVIEW OF TELECOMMUNICATION NETWORKS

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OVERVIEW OF TELECOMMUNICATION NETWORKS

Introduction

The telephone is a telecommunication device that is used to transmit and receive electronically or digitally encoded speech between two or more people conversing. It is one of the most common household appliances in the world today. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost any other user.

Telecommunication networks carry information signals among entities, which aregeographically far apart. An entity may be a computer or human being, a facsimile machine, a teleprinter, a data terminal and so on. The entities are involved in the process of information transfer that may be in the form of a telephone conversation (telephony) or a file transfer between two computers or message transfer between two terminals etc.

With the rapidly growing traffic and untargeted growth of cyberspace, telecommunication becomes a fabric of our life. The future challenges are enormous as we anticipate rapid growth items of new services and number of users. What comes with the challenge is a genuine need for more advanced methodology supporting analysis and design of telecommunication architectures. Telecommunication has evaluated and growth at an explosive rate in recent years and will undoubtedly continue to do so.

The communication switching system enables the universal connectivity. The universal connectivity is realized when any entity in one part of the world can communicate with any other entity in another part of the world. In many ways telecommunication will acts as a substitute for the increasingly expensive physical transportation.

The telecommunication links and switching were mainly designed for voice communication. With the appropriate attachments/equipments, they can be used to transmit data. A modern society, therefore needs new facilities including very high bandwidth switched data networks, and large communication satellites with small, cheap earth antennas.

Voice Signal Characteristics

Telecommunication is mainly concerned with the transmission of messages between two distant points. The signal that contains the messages is usually converted

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into electrical waves before transmission. Our voice is an analog signal, which has amplitude and frequency characteristics.Voice frequencies: - The range of frequencies used by a communication device determines the communication channel, communicating devices, and bandwidth or information carrying capacity. The most commonly used parameter that characterizes an electrical signal is its bandwidth of analog signal or bit rate if it is a digital signal. In telephone system, the frequencies it passes are restricted to between 300 to 3400 Hz.

In the field of telecommunications, a Telephone exchange or a Telephone switch is a system of electronic components that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make telephone calls "work" in the sense of making connections and relaying the speech information.

Switching system fundamentals

Telecommunications switching systems generally perform three basic functions: they transmit signals over the connection or over separate channels to convey the identity of the called (and sometimes the calling) address (for example, the telephone number), and alert (ring) the called station; they establish connections through a switching network for conversational use during the entire call; and they process the signal information to control and supervise the establishment and disconnection of the switching network connection.

In some data or message switching when real-time communication is not needed, the switching network is replaced by a temporary memory for the storage of messages. This type of switching is known as store-and-forward switching.

Signaling and control

The control of circuit switching systems is accomplished remotely by a specific form of data communication known as signaling. Switching systems are connected with one another by telecommunication channels known as trunks. They are connected with the served stations or terminals by lines.

In some switching systems the signals for a call directly control the switching devices over the same path for which transmission is established. For most modern switching systems the signals for identifying or addressing the called station are received by a central control that processes calls on a time-shared basis. Central controls receive and interpret signals, select and establish communication paths, and prepare signals for transmission. These signals include addresses for use at succeeding nodes or for alerting (ringing) the called station.

Most electronic controls are designed to process calls not only by complex logic but also by logic tables or a program of instructions stored in bulk electronic memory. 3

The tabular technique is known as translator. The electronic memory is now the most accepted technique and is known as stored program control (SPC). Either type of control may be distributed among the switching devices rather than residing centrally. Microprocessors on integrated circuit chips are a popular form of distributed stored program control.

Switching fabrics

Space and time division are the two basic techniques used in establishing connections. When an individual conductor path is established through a switch for the duration of a call, the system is known as space division. When the transmitted speech signals are sampled and the samples multiplexed in time so that high-speed electronic devices may be used simultaneously by several calls, the switch is known as time division.

In the early stages of development in telecommunication, manual switching methods were deployed. But later on to overcome the limitations of manual switching; automatic exchanges, having Electro-mechanical components, were developed. Strowger exchange, the first automatic exchange having direct control feature, appeared in 1892 in La Porte (Indiana). Though it improved upon the performance of a manual exchange it still had a number of disadvantages, viz., a large number of mechanical parts, limited availability, inflexibility, bulky in size etc. As a result of further research and development, Crossbar exchanges,having an indirect control system, appeared in 1926 in Sweden.

The Crossbar exchange improved upon many short- comings of the Strowger system. However, much more improvement was expected and the revolutionary change in field of electronics provided it. A large number of moving parts in Register, marker, Translator, etc., were replaced en-block by a single computer. This made the exchange smaller in size, volume and weight, faster and reliable, highly flexible, noise-free, easily manageable with no preventive maintenance etc.

Network Architecture.When electronic devices were introduced in the switching systems, a new concept

of switching evolved as a consequence of their extremely high operating speed compared to their former counter-parts, i.e., the Electro-mechanical systems, where relays, the logic elements in the electromechanical systems, have to operate and release several times which is roughly equal to the duration of telephone signals to maintain required accuracy.

Research on electronic switching started soon after the Second World War, but commercial fully electronic exchange began to emerge only about 30 years later. However, electronic techniques proved economic for common control systems much earlier. In electromechanical exchanges, common control systems mainly used switches

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and relays, which were originally designed for use in switching networks. In common controls, they are operated frequently and so wear out earlier. In contrast, the life of an electronic device is almost independent of its frequency of operation. This gave a motivation for developing electronic common controls and resulted in electronic replacements for registers, markers, translators etc. having much greater reliability than their electromechanical predecessors.

In electromechanical switching, the various functions of the exchange are achieved by the operation and release of relays and switch (rotary or crossbar) contacts, under the direction of a Control Sub-System. These contracts are hard - wired in a predetermined way. The exchange dependent data, such as subscriber’s class of service, translation and routing, combination signaling characteristics are achieved by hard-ware and logic, by a of relay sets, grouping of same type of lines, strapping on Main or Intermediate Distribution Frame or translation fields, etc. When the data is to be modified, for introduction of a new service, or change in services already available to a subscriber, the hardware change ranging from inconvenient to near impossible, are involved.

In an SPC exchange, a processor similar to a general-purpose computer is used to control the functions of the exchange. All the control functions, represented by a series of various instructions, are stored in the memory. Therefore the processor memories hold all exchange dependent data. such as subscriber date, translation tables, routing and charging information and call records. For each call processing step. e.g. for taking a decision according to class of service, the stored data is referred to, Hence, this concept of switching. The memories are modifiable and the control program can always be rewritten if the behavior or the use of system is to be modified. This imparts and enormous flexibility in overall working of the exchange.

Digital computers have the capability of handling many tens of thousands of instructions every second, Hence, in addition to controlling the switching functions the same processor can handle other functions also. The immediate effect of holding both the control programme and the exchange data, in easily alterable memories, is that the administration can become much more responsive to subscriber requirements. both in terms of introducing new services and modifying general services, or in responding to the demands of individual subscriber. For example, to restore service on payment of an overdue bill or to permit change from a dial instrument to a multi frequency sender, simply the appropriate entries in the subscriber data-file are to be amended. This can be done by typing- in simple instructions from a teletypewriter or visual display unit. The ability of the administration to respond rapidly and effectively to subscriber requirements is likely to become increasingly important in the future.

The modifications and changes in services which were previously impossible be achieved very simply in SPC exchange, by modifying the stored data suitably. In some cases, the subscribers can also be given the facility to modify their own data entries for

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supplementary services, such as on-demand call transfer, short code (abbreviated) dialing, etc.

The use of a central processor also makes possible the connection of local and remote terminals to carry out man-machine dialogue with each exchange. Thus, the maintenance and administrative operations of all the SPC exchanges in a network can be performed from a single centralized place. The processor sends the information on the performance of the network, such as, traffic flow, billing information, faults, to the centre, which carries out remedial measures with the help of commands. Similarly, other modifications in services can also be carried out from the remote centre. This allows a better control on the overall performance of the network.

As the processor is capable of performing operations at a very high speed, it has got sufficient time to run routine test programmes to detect faults, automatically. Hence, there is no need to carry out time consuming manual routine tests.

In an SPC exchange, all control equipment can be replaced by a single processor. The processor must therefore be quite powerful, typically it must process hundreds of calls per second, in addition to performing other administrative and maintenance tasks. However, totally centralized control has drawbacks. The software for such a central processor will be voluminous, complex, and difficult to develop reliably. Moreover, it is not a good arrangement from the point of view of system security, as the entire system will collapse with the failure of the processor. These difficulties can be overcome by decentralizing the control. Some routine functions such as scanning, signal distributing, marking, which are independent of call processing, can be delegated to auxiliary or peripheral processors.Stored program control (SPC) has become the principal type of control for all types of new switching systems throughout the world, including private branch exchanges, data and Telex systems. Two types of data are stored in the memories of electronic switching systems. One type is the data associated with the progress of the call, such as the dialed address of the called line. Another type, known as the translation data, contains infrequently changing information, such as the type of service subscribed to by the calling line and the information required for routing calls to called numbers. These translation data, like the program, are stored in a memory, which is easily read but protected to avoid accidental erasure. This information may be readily changed, however, to meet service needs. The flexibility of a stored program also aids in the administration and maintenance of the service so that system faults may be located quickly.

SPC exchanges can offer a wider range of facilities than earlier systems. In addition, the facilities provided to an individual customer can be readily altered by changing the customer’s class-of-service data stored in memory. Moreover, since the processor’s stored data can be altered electronically,some of these facilities can be controlled by customers. Examples include:-

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1. Call barring (outgoing or incoming): The customer can prevent unauthorized calls being made and can prevent incoming calls when wishing to be left in peace.

2. Call waiting: The ‘Call waiting’ service notifies the already busy subscriber of a third party calling him.

3. Alarm calls: The exchange can be instructed to call the customer at a pre-arranged time (e.g. morning alarm).

4. Call Forwarding: The subscriber having such a feature can enable the incoming calls coming to his telephone to be transferred to another number during his absence.

5. Conference calls: Subscriber can set up connections to more than one subscriber and conduct telephone conferences under the provision of this facility.

6. Dynamic Barring Facility: Subscriber having STD/ISD facilities can dynamically lock such features in their telephone to avoid misuse. Registering and dialing a secret code will extend such such a facility.

7. Abbreviated Dialing: Most subscribers very often call only limited group of telephone numbers. By dialing only prefix digit followed by two selection digits, subscribers can call up to 100 predetermined subscribers connected to any automatic exchange. This shortens the process of dialing all the digits.

8. Malicious call Identification: Malicious call identification is done immediately and the information is obtained in the print out form either automatically or by dialing an identification code.

9. Do Not Disturb: This facility enables the subscriber to free himself from attending his incoming calls. Using this facility the calls coming to the subscriber can be routed to an operator position or to an answering machine. The operator position or the machine can inform the calling subscriber that the called subscriber is temporarily inaccessible. Today SPC is a standard feature in all the electronic exchanges.

Implementation of Switching Network.

In an electronic exchange, the switching network is one of the largest sub-system in terms of size of the equipment. Its main functions are Switching (setting up temporary connection between two or more exchange terminations), Transmission of speech and signals between these terminations, with reliable accuracy.

There are two types of electronic switching system. viz. Space division and Time Division.Space Division switching System

In a space Division Switching system, a continuous physical path is set up between input and output terminations. This path is separate for each connection and is held for the entire duration of the call. Path for different connections is independent of each other. Once a continuous path has been established., Signals are interchanged between the two terminations. Such a switching network can employ either metallic or 7

electronic cross points. Previously, usage of metallic cross-points using reed relays and all were favored. They have the advantage of compatibility with the existing line and trunk signaling conditions in the network.

Time Division Switching SystemIn Time Division Switching, a number of calls share the same path on time

division sharing basis. The path is not separate for each connection, rather, is shared sequentially for a fraction of a time by different calls. This process is repeated periodically at a suitable high rate. The repetition rate is 8 KHz, i.e. once every 125 microseconds for transmitting speech on telephone network, without any appreciable distortion. These samples are time multiplexed with staggered samples of other speech channels, to enable sharing of one path by many calls. The Time Division Switching was initially accomplished by Pulse Amplitude

Modulation (PAM) Switching. However, it still could not overcome the performance limitations of signal distortion noise, cross-talk etc. With the advent of Pulse Code Modulation (PCM), the PAM signals were converted into a digital format overcoming the limitations of analog and PAM signals. PCM signals are suitable for both transmission and switching. The PCM switching is popularly called Digital Switching.Digital Switching Systems

A Digital switching system, in general, is one in which signals are switched in digital form. These signals may represent speech or data. The digital signals of several speech samples are time multiplexed on a common media before being switched through the system.

To connect any two subscribers, it is necessary to interconnect the time-slots of the two speech samples, which may be on same or different PCM highways. The digitalized speech samples are switched in two modes, viz., Time Switching and Space Switching. This Time Division Multiplex Digital Switching System is popularly known as Digital Switching System.

The ESS No.1 system was the first fully electronic switching system but not digital. But later came ESS No.4 system which was digital for trunk portion only. When designed, the cost of A/D conversion (CODEC) on each subscriber line was seen as prohibitive. So the ESS No.4 system was acting as a Trunk/Tandem exchange but not as a local exchange. So the main difficulty for implementing a digital local exchange was the implementation of the subscriber line interface. This was solved by the introduction of Integrated Circuits, which made the digital local exchange economically feasible. This implementation handles the following functions:

B-Battery feedO-Over-voltage protection (from lightning and accidental power line contact)R-RingingS-Supervisory SignalingC-Coding (A/D inter conversion & low pass filtering)

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H-Hybrid (2W to 4W conversion)T-Testing the connectivity of Subscriber

Examples of digital exchanges (switching systems) include CDOT, OCB, AXE, EWSD, 5ESS etc.

The general architecture of a Digital Switching System is depicted in fig2General architecture of Digital Switching System

Figure-2

The next evolutionary step was to move the PCM codec from the exchange end of the customer’s line to the customer’s end. This provides digital transmission over the customer’s line, which can have a number of advantages. Consider data transmission. If there is an analog customer’s line, a modem must be added and data can only be transmitted at relatively slow speeds. If the line is digital, data can be 9

Subs interface

Other exchanges

N x 2 Mbpslinks

CONTROLPROCESSOR

Operation &Maintenance

Trunks interface

Other auxiliary inter facesSuch as,(a) Tone generator(b) Frequency receives(c) Conference call facility(d) CCS# 7 Protocol

Manager(e) V 5.2 access manager

Digital Switch

transmitted by removing the codec (instead of adding a modem). Moreover, data can be transmitted at 64 kbit/s instead of at, say, 2.4 kbit/s. Indeed, any form of digital signal can be transmitted whose rate does not exceed 64 kbit/s. This can include high-speed fax, in addition to speech and data.

This concept had led to the evolution of Integrated services digital network (ISDN), in which the customer’s terminal equipment and the local digital exchange can be used to provide many different services, all using 64 kbit/s digital streams. In simple terms, we can say ISDN provides end-to-end digital connectivity.

Access to an ISDN is provided in two forms:

1. Basic-Rate Access (BRA) The customer’s line carries two 64 kbit/s “B” channels plus a 16 kbit/s

“D” channel (a common signaling channel) in each direction.

2. Primary Rate Access (PRA) The line carries a complete PCM frame at 2 Mbit/s in each direction.

This gives the customer 30 circuits at 64 kbit/s plus a common signaling channel, also at 64 kbit/s.

Control of switching systems

Switching systems have evolved from being manually controlled to being controlled by relays and then electronically. The change from the manual system to the Strowger step-by-step system brought about a change from centralized to distributed control. However, as systems developed and offered more services to customers, it became economic to perform particular functions in specialized equipments that were associated with connections only when required, thus, common control was introduced.

Later, the development of digital computer technology enabled different functions to be performed by the same hardware by using different programs; thus switching system entered the era of stored-program control (SPC).

There are basically two approaches to organizing stored program control: centralized and distributed. Early electronic switching systems (ESS) developed during the period 1970-75 almost invariably used centralized control. Although many present day exchange designs continue to use centralized SPC, with the advent of low cost powerful microprocessors and very large scale integration (VLSI) chips such as programmable logic arrays (PLA) and programmable logic controllers (PLC), distributed SPC is gaining popularity.

The figure below shows the evolution of electronic switching systems from the manual switching systems. The figure also depicts the changing scenario from digital switching to Broadband where the focus will be for high bit rate data transmissions.10

Development of exchanges

Figure 3

Local and trunk NetworkTrunk Lines

The term Trunk Line in telecommunications refers to the high-speed connection between telephone central offices in the Public Switched Telephone Network (PSTN). Trunk lines are always digital. The wiring between central offices was originally just pairs of twisted copper wire (the twists in the wiring prevented things known as crosstalk and noise). Because it is expensive to string up (or lay trenches for buried cables), the phone company researched ways in which to carry more data over the existing copper lines. This was achieved by using time-division multiplexing. Later, when fiber-optic technology became available, phone companies upgraded their trunk lines to fiber optics and used statistical time-division multiplexing, synchronous digital heirarchy, coarse or

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dense wave division multiplexing and optical switching to further improve transmission speeds.

The signaling information exchanged between different exchanges via inter exchange trunks for the routing of calls is termed as Inter exchange Signaling. Earlier in band /out of band frequencies were used for transmitting signaling information. Later on, with the emergence of PCM systems, it was possible to segregate the signaling from the speech channel. A trunk line is a circuit connecting telephone switchboards (or other switching equipment), as distinguished from local loop circuit which extends from telephone exchange switching equipment to individual telephones or information origination/termination equipment.

When dealing with a private branch exchange (PBX), trunk lines are the phone lines coming into the PBX from the telephone provider. This differentiates these incoming lines from extension lines that connect the PBX to (usually) individual phone sets. Trunking saves cost, because there are usually fewer trunk lines than extension lines, since it is unusual in most offices to have all extension lines in use for external calls at once. Trunk lines transmit voice and data in formats such as analog, T1, E1, ISDN or PRI. The dial tone lines for outgoing calls are called DDCO (Direct Dial Central Office) trunks. A signal travelling over a trunk line is not actually flowing any faster. The electrical signal on a voice line takes the same amount of time to traverse the wire as a similar length trunk line. What makes trunk lines faster is that the signal has been altered to carry more data in less time using more advanced multiplexing and modulation techniques. If you compared a voice line and a trunk line and put them side by side and observed them, the first pieces of information arrive simultaneously on both the voice and trunk line. However, the last piece of information would arrive sooner on the trunk line. No matter what, you can't break the laws of physics. Electricity over copper or laser light over fiber optics, you cannot break the speed of light--though that has rarely stopped uneducated IT or IS managers from demanding that cabling perform faster instead of upgrading equipment.

Trunk lines can contain thousands of simultaneous calls that have been combined using time-division multiplexing. These thousands of calls are carried from one central office to another where they can be connected to a de-multiplexing device and switched through digital access cross connecting switches to reach the proper exchange and local phone number.

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Local and trunk Network

S : Remote line unitL : Local subscriber exchangeTR : Transit exchangeCID : Outgoing international exchange CIA : Incoming international exchangeCTI : International transit exchange

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09 TR TR L S

s

S

L

CID

TR

TR

L S

S

CIA

CTI

What is Trunking?

In telecommunications systems, trunking is the aggregation of multiple user circuits into a single channel. The aggregation is achieved using some form of multiplexing. Trunking theory was developed by Agner Krarup Erlang, Erlang based his studies of the statistical nature of the arrival and the length of calls. The Erlang B formula allows for the calculation of the number of circuits required in a trunk based on the Grade of Service and the amount of traffic in Erlangs the trunk needs cater for.

Definition

In order to provide connectivity between all users on the network one solution is to build a full mesh network between all endpoints. A full mesh solution is however impractical, a far better approach is to provide a pool of resources that end points can make use of in order to connect to foreign exchanges. The diagram below illustrates the where in a telecommunication network trunks are used.

A Modern Telephone Network Indicating where trunks are used. SLC - Subscriber

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line concentrator

LE – Local Exchange

TDM TAX –II – Level II Tax

TDM TAX –I – Level –I Tax

Level I Taxs are connected to the Gateway.

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Call routing

Routing in the PSTN is the process used to route telephone calls across the public switched telephone network. This process is the same whether the call is made between two phones in the same locality, or across two different continents.

Relationship between exchanges and operators

Telephone calls must be routed across a network of multiple exchanges, potentially owned by different telephone operators. The exchanges are all are inter-connected together using trunks. Each exchange has many "neighbours", some of which are also owned by the same telephone operator, and some of which are owned by different operators. When neighbouring exchanges are owned by different operators, they are known as interconnect points.

This means that there is really only one virtual network in the world that enables any phone to call any other phone. This virtual network comprises many interconnected operators, each with their own exchange network. Every operator can then route calls directly to their own customers, or pass them on to another operator if the call is not for one of their customers.

The PSTN is not a fully meshed network with every operator connected to every other - that would be both impractical and inefficient. Therefore calls may be routed through intermediate operator networks before they reach their final destination. One of the major problems in PSTN routing is determining how to route this call in the most cost effective and timely manner.

Call routing

Each time a call is placed for routing, the destination number (also known as the called party) is entered by the calling party into their terminal. The destination number generally has two parts, a prefix which generally identifies the geographical location of the destination telephone, and a number unique within that prefix that determines the specific destination terminal. Sometimes if the call is between two terminals in the same local area (that is, both terminals are on the same telephone exchange), then the prefix may be omitted.

When a call is received by an exchange, there are two treatments that may be applied:

Either the destination terminal is directly connected to that exchange, in which case the call is placed down that connection and the destination terminal rings.

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Or the call must be placed to one of the neighbouring exchanges through a connecting trunk for onward routing.

Each exchange in the chain uses pre-computed routing tables to determine which connected exchange the onward call should be routed to. There may be several alternative routes to any given destination, and the exchange can select dynamically between these in the event of link failure or congestion.

The routing tables are generated centrally based on the known topology of the network, the numbering plan, and analysis of traffic data. These are then downloaded to each exchange in the telephone operators network. Because of the hierarchical nature of the numbering plan, and its geographical basis, most calls can be routed based only on their prefix using these routing tables.

Some calls however cannot be routed on the basis of prefix alone, for example non-geographical numbers, such as toll-free or freephone calling. In these cases the Intelligent Network is used to route the call instead of using the pre-computed routing tables.

In determining routing plans, special attention is paid for example to ensure that two routes do not mutually overflow to each other, otherwise congestion will cause a destination to be completely blocked.

According to Braess' paradox, the addition of a new, shorter, and lower cost route can lead to an increase overall congestion[. The network planner must take this into account when designing routing paths.

One approach to routing involves the use of Dynamic Alternative Routing (DAR). DAR makes use of the distributed nature of a telecommunications network and its inherent randomness to dynamically determine optimal routing paths. This method generates a distributed, random, parallel computing platform that minimises congestion across the network, and is able to adapt to take changing traffic patterns and demands into account.

Routing can be loosely described as the process of getting from here to there. Routing may be discussed in the context of telephone networks or computer networks. In telephone networks, routing is facilitated by switches in the network, whereby in computer networks routing is performed by routers in the network.

Definition: Routing in telephone networks

Routing in the context of telephone networks is the selection of a specific circiut group, for a given call or traffic stream, at an exchange in the network . "The objective of routing is to establish a successful connection between any two exchangesin the network" . By selecting routes that meet the constraints set by the user traffic and the network, routing determines which network resources (circuit group) should be used to transport which user traffic.

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Different networks employ different routing techniques, but all communication networks share a basic routing functionality based on three core routing functions

Assembling and distributing information on the state of the network and user traffic that is used to generate and select routes.

Generating and selecting feasible and optimal routes based on network and user traffic state information. Forwarding user traffic along the selected routes. The public switched telephone network (PSTN) architecture is made up of a hierarchy of exchanges (e.g local and regoinal exchanges) with each level of the hierarchy performing different functions . Two adjacent exchanges in the network may be connected by several direct routes consisting of one or more circuits .In circuit-switched networks, such as the PSTN, switching and transmission resources are dedicated to a call along the path from source to destination for the complete duration of the call. Routing decisions are imperative in facilitating this process as they determine the most efficient links to use to connect users for a call . Routing in the PSTN is done using a hop-by-hop approach . When a user wants to make a call, they dial the destination number to which the call should be routed. This destination number is made up of a prefix (area code or national destination network), which identifies the geographical location of the called party, and a unique number (the subscriber number) linked to the prefix that identifies the exact destination to which the call should be routed The end exchange to which the calling party is connected (the originating exchange) uses the area code to identify the outgoing circuit group connecting to the first choice adjacent exchange en-route This circuit group is called the first choice route and is obtained using a routing table at the originating switch . The function of the switch at the originating end exchange is to connect the switch input port to which the calling user is connected to a free outgoing circuit group in the first choice group . If all the circuits along the first choice route are fully occupied, the switch then attempts to use an alternative route circuit group to route the call to the destination exchange . The originating exchange then forwards the address to the adjacent exchange (first choice or alternate route), and the procedure is repeated at the adjacent exchange in order to reach the destination end exchange to which the called party is connected . When the address reaches the destination exchange, it only needs to process the last part of the address to identify the switch input port that the called party is connected .Routing directs forwarding . Forwarding of traffic can be done using connection-oriented or connectionless approaches . In connection-oriented forwrding, forwarding instructions are installed in all the switches along a designated route before the route can be used to transport traffic . Traffic forwarded using the connectionless approach carries its own forwarding information either as precise routing commands for each switch along a route or as hints that may be autonomously interpreted by any switch in the network .

In PSTN, forwarding of traffic is based on the connection-oriented approach. Call routing is achieved using pre-computed routing tables, containing all the possible pre-defined routes for a connection, at each switch .The pre-defined routes specified in the routing table include information of a direct route (or routes) to be used under normal traffic and network conditions (e.g no link failure or network congestion) as well as alternative

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routes that should be used in the event that all circuits along the direct route are fully occupied . An alternative route may be an indirect route consisting of several circuit groups connecting two exchanges via other exchanges . The following example illustrates the use of an alternative route to connect two exchanges in the event of the direct route being congetsed.

A Typical Telephone Exchange -OCB-283 FUNCTIONAL ARCHITURE

The Alcatel E10 system is located at the heart of the telecommunication networks concerned. It is made up of three independent functional units:- The “Subscriber Access Subsystem” which carries out connection of analogue and

digital subscriber lines,

- “Connection and Control” which carries out connections and processing of calls,

- “Operation and Maintenance” which is responsible for all functions needed by the network operating authority.

Each functional unit is equipped with softwares which are appropriate for handling the functions for which it is responsible.

Synchronization and Time Base Station STS

Time base (BT)

The BT ensures times distribution for LR and PCM to provide the synchronization, and also for working out the exchange clock.Time distribution is tripled.

Time generation can be either autonomous or slaved to an external rhythm with a view to synchronise the system with the network

Auxiliary Equipment Control Station SMA

Auxiliary equipment manager (ETA)

The ETA Supports:

- The tone generators (GT).

- The frequency receiving and generation (RGF) devices,

- Conference circuits (CCF),

- The exchange clock

CCS7 protocol handler (PUPE) and CCS7 controller (PC): CCITT No. 7 protocol processing

For connection of 64 kbit/s signaling channels, semi- permanent connections are established via the connection matrix, to the PUPE which processes the CCITT No. 7 protocol.

More precisely, the PUPE function carries out the following:

- “signaling channel” Level 2 processing,

- the “message routing” function19

(Part of Level 3). The PC carries out:

- the “network management” function (part of Level 3),

- PUPE defence,

- Various observation tasks which are not directly linked to CCITT No. 7.

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OCB 283

SUBCRIBER

ACCESS

SUBSYSTEM

CONNECTION

AND

CONTROL

OPERATIONAND

MAINTENANCE

DATANETWORK

TELEPHONENETWORK

VALUE ADDED NETWORK

CCITT N07 SIGNALLING NETWORK

NT

PABX

ALCATEL 1000 E10 OCB 283

OPERATION AND MAINTENANCE

NETWORK

Host switching matrix (SMX)

The SMX is a square connection matrix with a single time stage, T, duplicated in full, which enables up to 2048 matrix links (LR) to be connected.

A matrix link LR is an internal PCM, with 16 bits per channel (32 channels). The MCX can execute the following:

1) an unidirectional connection between any incoming channel and any out going channel. There can be as many simultaneous connections as there are outgoing channels. It should be remembered that a connection consists of allocating the information contained within an incoming channel to an outgoing channel,

2) connection between any incoming channel and any M outgoing channels,

3) connection of N incoming channels belonging to one frame structure of any multiplex onto N outgoing channels which belong to the same frame structure, abiding to the integrity and sequencing of the frame received. This function is referred to as “connection with N x 64 kbit/s”.

The MCX is controlled by the COM function (matrix switch controller) to ensure the:

- set up and breakdown of the connections by access to the matrix command memory. This access is used to write at the output T.S. address the incoming T.S. address

- defense of the connections. Security of the connections in order to assure a good data switching.

Truck Control Station SMT

PCM controller (URM)

The URM provides the interface between external PCMs and the OCB283. These PCM come from either:

- a remote subscriber digital access unit (CSN) or from a remote electronic satellite concentrator CSE,

- another switching centre, on channel-associated signalling or CCITT No.7,

- the digital recorded announcement equipment

In particular, the URM carries out the following functions:

- HDB3 conversion to binary (PCM matrix link),

- binary conversion to HDB3 (matrix link” PCM),

- extraction and pre-processing of the channel-associated signalling of T.S.16 (PCM command),

21

- transmission of channel-associated signalling in T.S.16 (command PCM).

Main Control Station SMC

Call handler (MR)

The MR is responsible for the establishment and breaking off of communications.

The call handler takes the decisions necessary for processing of communications in terms of the signaling received, after consultation of the subscriber and analysis database manager (TR) if necessary. The call handler processes new calls and handling-up operations, releases equipment, commands switching on and switching off etc.

In addition, the call handler is responsible for different management tasks (control of tests of circuits, sundry observations).

Operation and maintenance function (OM) SMM

The functions of the operation and maintenance subsystem are carried out by the operation and maintenance software OM).

The operating authority accesses all hardware and software equipment of the Alcatel 1000 E10 system via computer terminals belonging to the operation and maintenance subsystem: consoles, magnetic media, intelligent terminal. These functions can be grouped into 2 categories:

- operation of the telephone application,

- operation and maintenance of the system.

In addition, the operation and maintenance subsystem carries out:

- loading of softwares and of data for connection and command and for the subscriber digital access units,

- temporary backup of detailed billing information,

- centralisation of alarm data coming from connection and control stations, via alarm rings,

- central defence of the system.

Finally, the operation and maintenance subsystem permits two-way communication with operation and maintenance networks, at regional or national level (TMN).

CSN - digital satellite center

The digital satellite center [CSN center satellite numerique) is a subscriber connection unit on which both analogue and digital subscribers can be connected.

Its design and composition enable the CSN to fit into an existing network and can be

connected to time-based systems using the CCITT N° 7 type of semaphore signalling.

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The CSN is a connection unit designed to adapt to a variety of geographical situation: it can be either local [CSNL] or distant [CSND] with respect to the connecting switch.

A Typical Telephone Exchange -OCB-283

CSN : Digital satellite center

SMC : Main Control Station

SMA : Auxiliary Equipment Control Station23

SMXSTS 1 x 3

CSNNNNLCS

NNDCSED

Circuits and announcement machine

LR

SMT( 1 TO 28) X 2

SMA( 2 TO 37)

SMC2 TO 14

1 TO 4 MAS

1 MISSMM1 x 2

LRLR

ALT

MN

SMT : Truck Control Station

SMX : Matrix Control Station

SMM : Maintenance Station

STS : Synchronization and Time Base Station

Summer Training, Overview of Telecommunication Networks-II

Overview of Telecommunication Networks – IIInstitutional mechanism and roleIntroduction: All industries operate in a specific environment which keeps changing and thefirms in the business need to understand it to dynamically adjust their actions for best results.Like minded firms get together to form associations in order to protect their commoninterests. Other stake holders also develop a system to take care of their issues. Governmentsalso need to intervene for ensuring fair competition and the best value for money for itscitizens. This handouts gives exposure on the Telecom Environment in India and also dwellson the role of international bodies in standardizing and promoting Telecom Growth in theworld.

Lesson Plan Institutional Mechanism and role & Telecom Eco systemo National DOT, TRAI,TDSAT, TEC,CDOTo International Standardisation bodies- ITU,APT,ETSI etc Licensed Telecommunication services of DOT Various Trade associations, Network Operators, Manufacturers, service providers,service provisioning and retailing, billing and OSS Job opportunities in telecom Market, government and statutory bodies

Assignment: Explore designated websites of institutions and companiesInstitutional Framework: It is defined as the systems of formal laws, regulations, andprocedures, and informal conventions, customs, and norms, that broaden, mold, and restrainsocio-economic activity and behaviour. In India, The Indian telegraph act of 1885 amendedfrom time to time governs the telecommunications sector. Under this act, the government is

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in-charge of policymaking and was responsible for provisioning of services till the opening oftelecom sector to private participation. The country has been divided into units called Circles,Metro Districts, Secondary Switching Areas (SSA), Long Distance Charging Area (LDCA)and Short Distance Charging Area (SDCA). Major changes in telecommunications in Indiabegan in the 1980s. The initial phase of telecom reforms began in 1984 with the creation ofCenter for Department of Telematics (C-DOT) for developing indigenous technologies andprivate manufacturing of customer premise equipment. Soon after, the Mahanagar TelephoneNigam Limited (MTNL) and Videsh Sanchar Nigam Limited (VSNL) were set up in 1986.The Telecom Commission was established in 1989. A crucial aspect of the institutionalreform of the Indian telecom sector was setting up of an independent regulatory body in1997 – the Telecom Regulatory Authority of India (TRAI), to assure investors that the sectorwould be regulated in a balanced and fair manner. In 2000, DoT corporatized its serviceswing and created Bharat Sanchar Nigam Limited. Further changes in the regulatory systemtook place with the TRAI Act of 2000 that aimed at restoring functional clarity andimproving regulatory quality and a separate disputes settlement body was set up calledTelecom Disputes Settlement and Appellate Tribunal (TDSAT) to fairly adjudicate anydispute between licensor and licensee, between service provider, between service providerand a group of consumers. In October 2003, Unified Access Service Licenses regime forbasic and cellular services was introduced. This regime enabled services providers to offerfixed and mobile services under one license. Since then, Indian telecom has seenunprecedented customer growth crossing 600 million connections. India is the fourth largesttelecom market in Asia after China, Japan and South Korea. The Indian telecom network isthe eighth largest in the world and the second largest among emerging economies. A brief ontelecom echo system and various key elements in institutional framework is given below:

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Department of Telecommunications: In India, DoT is the nodal agency for taking care oftelecom sector on behalf of government. Its basic functions are:_ Policy Formulation_ Review of performance_ Licensing_ Wireless spectrum management_ Administrative monitoring of PSUs_ Research & Development_ Standardization/Validation of Equipment_ International RelationsMain wings within DoT: Telecom Engineering Center (TEC) USO Fund Wireless Planning & Coordination Wing (WPC) Telecom Enforcement, Resource and Monitoring (TERM) Cell Telecom Centers of Excellence (TCOE)Public Sector Units Bharat Sanchar Nigam Limited(BSNL) Indian Telephone Industries Limited (ITI) Mahanagar Telephone Nigam Limited(MTNL) Telecommunications Consultants India Limited(TCIL)R & D Unit Center for development of Telematics (C-DoT)The other key governmental institutional units are TRAI & TDSAT. Important units arebriefed below:Telecom Engineering Center (TEC): It is a technical body representing the interest ofDepartment of Telecom, Government of India. Its main functions are: Specification of common standards with regard to Telecom networkequipment, services and interoperability. Generic Requirements (GRs), Interface Requirements (IRs) Issuing Interface Approvals and Service Approvals Formulation of Standards and Fundamental Technical Plans Interact with multilateral agencies like APT, ETSI and ITU etc. for standardisation Develop expertise to imbibe the latest technologies and results of R&D Provide technical support to DOT and technical advice to TRAI & TDSAT Coordinate with C-DOT on the technological developments in the Telecom Sectorfor policy planning by DOT www.tec.gov.inUniversal Service Obligation Fund (USO): This fund was created in 2002. This fund is

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managed by USO administrator. All telecom operators contribute to this fund as pergovernment policy. The objective of this fund is to bridge the digital divide i.e. ensureequitable growth of telecom facilities in rural areas. Funds are allocated to operators who bidlowest for providing telecom facilities in the areas identified by USO administrator.WIRELESS PLANNING & COORDINATION (WPC) This unit was created in 1952 and is theNational Radio Regulatory Authority responsible for Frequency Spectrum Management,including licensing and caters for the needs of all wireless users (Government and Private) inthe country. It exercises the statutory functions of the Central Government and issues licensesto establish, maintain and operate wireless stations. WPC is divided into major sections likeLicensing and Regulation (LR), New Technology Group (NTG) and Standing AdvisoryCommittee on Radio Frequency Allocation (SACFA). SACFA makes the recommendationson major frequency allocation issues, formulation of the frequency allocation plan, makingrecommendations on the various issues related to International Telecom Union (ITU), to sortout problems referred to the committee by various wireless users, Siting clearance of allwireless installations in the country etc.Telecom Enforcement, Resource and Monitoring (TERM) Cell: In order to ensure thatservice providers adhere to the licence conditions and for taking care of telecom networksecurity issues, DoT opened these cells in 2004 and at present 34 cells are operating invarious Circles and big districts in the country. Key functions of these units are Inspection ofpremises of Telecom and Internet Service Providers, Curbing illegal activities in telecomservices, Control over clandestine / illegal operation of telecom networks by vested interestshaving no license, To file FIR against culprits, pursue the cases, issue notices indicatingviolation of conditions of various Acts in force from time to time, Analysis ofcall/subscription/traffic data of various licensees, arrangement for lawful interception /

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monitoring of all communications passing through the licensee’s network, disastermanagement, network performance monitoring, Registration of OSPs and Telemarketers inLicense Service Areas etc..Telecom Centers of Excellence (TCOE): (www.tcoe.in) The growth of IndianTelecommunications sector has been astounding, particularly in the last decade. This growthhas been catalysed by telecommunications sector liberalization and reforms. Some of theareas needing immediate attention to consolidate and maintain the growth are: Capacity building for industry talent pool Continuous adaptation of the regulatory environment to facilitate induction/adoptation of high potential new technologies and business models Bridging of high rural - urban teledensity/digital divide Faster deployment of broadband infrastructure across the countryCentres of Excellence have been created to work on (i) enhancing talent pool, (ii)technological innovation, (iii) secure information infrastructure and (iv) bridging of digitaldivide. These COEs are also expected to cater to requirements of South Asia as regionalleaders. The main sponsor (one of the telecom operators), the academic institute where theCenters are located and the tentative field of excellence are enumerated in the table below:Field of Excellence in Telecom Associated Institute SponsorNext Generation Network & NetworkTechnologyIIT, Kharagpur Vodafone EssarTelecom Technology & Management IIT, Delhi Bharti AirtelTechnology Integration, Multimedia &Computational MathsIIT, Kanpur BSNLTelecom Policy, Regulation, Governance,Customer Care & MarketingIIM, Ahmedabad IDEA CellularTelecom Infrastructure & Energy IIT, Chennai RelianceDisaster Management of Info systems &Information SecurityIISc, Bangalore AircelRural Application IIT Mumbai Tata Telecom

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Spectrum Management (Proposed) WPC, Chennai Govt with IndustryconsortiumTelecom Regulatory Authority of India (TRAI): TRAI was established under TRAI Act1997 enacted on 28.03.1997. The act was amended in 2000. Its Organization setup consists ofOne Chairperson, Two full-time members & Two part-time members. Its primary role is todeals with regulatory aspects in Telecom Sector & Broadcasting and Cable services. TRAIhas two types of functions as mentioned below: Mandatory Functionso Tariff policieso Interconnection policieso Quality of Serviceo Ensure implementation of terms and conditions of license Recommendatory Functionso New license policieso Spectrum policieso Opening of sectorwww.trai.gov.inTelecom Dispute Settlement Appellate Tribunal (TDSAT): TDSAT was established inyear 2000 by an amendment in TRAI act by transferring the functions of dispute handling tonew entity i.e. TDSAT. The organization setup consists of one Chairperson & two full-timemembers. Its functions are: Adjudicate any dispute betweeno licensor and licenseeo two or more licenseeso group of consumers Hear & dispose off appeal against any direction, decision or order of the Authorityunder TRAI Actwww.tdsat.nic.inKey International Standardization Bodies for Telecom sector:ITU is the leading United Nations agency for information and communication technologyissues, and the global focal point for governments and the private sector in developingnetworks and services. For nearly 145 years, ITU has coordinated the shared global use ofthe radio spectrum, promoted international cooperation in assigning satellite orbits, worked toimprove telecommunication infrastructure in the developing world, established the worldwide29

standards that foster seamless interconnection of a vast range of communications systems andaddressed the global challenges of our times, such as mitigating climate change andstrengthening cybersecurity. Vast spectrum of its work area includes broadband Internet tolatest-generation wireless technologies, from aeronautical and maritime navigation to radioastronomy and satellite-based meteorology, from convergence in fixed-mobile phone,Internet access, data, voice and TV broadcasting to next-generation networks. ITU alsoorganizes worldwide and regional exhibitions and forums, such as ITU TELECOM WORLD,bringing together the most influential representatives of government and thetelecommunications and ICT industry to exchange ideas, knowledge and technology for thebenefit of the global community, and in particular the developing world. ITU is based inGeneva, Switzerland, and its membership includes 191 Member States and more than 700Sector Members and Associates. On 1 January 2009, ITU employed 702 people from 83different countries. The staff members are distributed between the Union's Headquarters inGeneva, Switzerland and eleven field offices located around the world. www.itu.intAsia Pacific Telecommunity: Headquartered at Bangkok, the APT is a unique organizationof Governments, telecom service providers, manufactures of communication equipment,research & development organizations and other stake holders active in the field ofcommunication and information technology. APT serves as the focal organization forcommunication and information technology in the Asia Pacific region. The APT has 34Members, 4 Associate Members and 121 Affiliate Members. The objective of theTelecommunity is to foster the development of telecommunication services and informationinfrastructure throughout the region with a particular focus on the expansion thereof in lessdeveloped areas. APT has been conducting HRD Programme for developing the skills ofAPT Members to meet the objectives of APT. The topics include Information

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Communication Technologies (ICT), Network and Information Security, Finance and Budget,Telecommunication Management, Mobile Communications, Multimedia, SatelliteCommunication, Telecommunications and ICT Policy and Regulation, BroadbandTechnologies, e-Applications, Rural Telecommunications Technologies, IP Networks andServices, Customer Relations, etc. www.aptsec.orgThe European Telecommunications Standards Institute (ETSI) produces globallyapplicablestandards for Information and Communications Technologies (ICT), includingfixed, mobile, radio, converged, broadcast and internet technologies. It is officiallyrecognized by the European Union as a European Standards Organization. ETSI is a not-forprofitorganization with more than 700 ETSI member organizations drawn from 62 countriesacross 5 continents world-wide. ETSI unites Manufacturers, Network operators, NationalAdministrations , Service providers, Research bodies, User groups , Consultancies. Thiscooperation has resulted in a steady stream of highly successful ICT standards in mobile,fixed, and radio communications and a range of other standards that cross these boundaries,including Security, Satellite, Broadcast, Human Factors, Testing & Protocols, Intelligenttransport, Power-line telecoms, eHealth, Smart Cards, Emergency communications, GRID &Clouds, Aeronautical etc. ETSI is consensus-based and conducts its work throughTechnical Committees, which produce standards and specifications, with the ETSI GeneralAssembly and Board. www.etsi.orgBSNL: Bharat Sanchar Nigam Limted was formed in year 2000 and took over the serviceproviders role from DoT. Today, BSNL has a customer base of over 9 crore and is the fourthlargest integrated telecom operator in the country. BSNL is the market leader in Broadband,landline and national transmission network. BSNL is also the only operator covering over 5lakh village with telecom connectivity. Area of operation of BSNL is all India except Delhi &Mumbai.

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MTNL: Mahanagar Telephone Nigam Limited, formed in 1984 is the market leader inlandline and broadband in its area of operation. www.mtnl.net.inTCIL: TCIL, a prime engineering and consultancy company, is a wholly owned Governmentof India Public Sector Enterprise. TCIL was set up in 1978 for providing Indian telecomexpertise in all fields of telecom, Civil and IT to developing countries around the world. Ithas its presence in over 70 countries. www.tcil-india.comITI: Indian telephone Industries is the oldest manufacturing unit for telephone instruments.To keep pace with changing times, it has started taking up manufacturing of new technologyequipment such as GSM, OFC equipment, Invertors, Power plants, Defense equipments,Currency counting machines etc. www.itiltd-india.comCentre for Development of Telematics (CDoT): This is the R & D unit under DoT setup in1984. The biggest contribution of this centre to Indian telecom sector is the development oflow capacity (128 port) Rural automatic Exchange (RAX) which enabled provisioning oftelephone in even the smallest village. This was specially designed to suit Indianenvironment, capable of withstanding natural temperature and dusty conditions.Prominent Licenses provided by DoT:o Access Service (CMTS & Unified Access Service): The Country is divided into 23Service Areas consisting of 19 Telecom Circle Service Areas and 4 Metro Service Areasfor providing Cellular Mobile Telephone Service (CMTS). Consequent uponannouncement of guidelines for Unified Access (Basic& Cellular) Services licenses on11.11.2003, some of the CMTS operators have been permitted to migrate from CMTSLicense to Unified Access Service License (UASL). No new CMTS and Basic servicelicenses are being awarded after issuing the guidelines for Unified access ServiceLicence(UASL). As on 31st March 2008, 39 CMTS and 240 UASL licenses operated.o 3G & BWA (Broadband Wireless Access): Department of Telecom started the auctionprocess for sale of spectrum for 3G and BWA (WiMax) in April 2010 for 22 services

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areas in the country. BSNL & MTNL have already been given spectrum for 3G and BWAand they need to pay the highest bid amount as per auction results. BSNL & MTNL bothare providing 3G services. BSNL has rolled out its BWA service by using WiMaxtechnology.o Mobile Number Portability (MNP) Service: Licenses have been awarded to twooperators to provide MNP in India. DoT is ensuring the readiness of all mobile operatorsand expects to start this service any time after June 2010.o Infrastructure Provider: There are two categories IP-I and IP-II. For IP-I the applicantcompany is required to be registered only. No license is issued for IP-I. Companiesregistered as IP-I can provide assets such as Dark Fibre, Right of Way, Duct space andTower. This was opened to private sector with effect from 13.08.2000. An IP-II licensecan lease / rent out /sell end to end bandwidth i.e. digital transmission capacity capable tocarry a message. This was opened to private sector with effect from 13.08.2000. Issuanceof IP-II Licence has been discontinued w.e.f. 14.12.05o INMARSAT : INMARSAT (International Maritime Satellite Organisation) operates aconstellation of geo-stationary satellites designed to extend phone, fax and datacommunications all over the world. Videsh Sanchar Nigam Ltd (VSNL) is permittedto provide Inmarsat services in India under their International Long Distance(ILD)licence granted by Department of Telecommunications(DoT). VSNL has commissionedtheir new Land Earth Station (LES) at Dighi, Pune compatible with 4th generationINMARSAT Satellites (I-4) and INMARSAT-B, M, Mini-M & M-4 services are nowbeing provided through this new LES after No Objection Certificate (NOC) is issued byDoT on case by case basis.o National Long Distance: There is no limit on number of operators for this service andlicense is for 20 years.o International Long Distance: This was opened to private sector on 1st April 2002 withno limit on number of operators. The license period is 20 years.

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o Resale of IPLC: For promoting competition and affordability in International PrivateLeased Circuits (IPLC) Segment, Government permitted the “Resale of IPLC” byintroducing a new category of License called as – “Resale of IPLC” Service License witheffect from 24th September 2008. The Reseller can provide end-to-end IPLC betweenIndia and country of destination for any capacity denomination. For providing the IPLCservice, the Reseller has to take the IPLC from International Long Distance (ILD) ServiceProviders licensed and permitted to enter into an arrangement for leased line with AccessProviders, National Long Distance Service Providers and International Long DistanceService Providers for provision of IPLC to end customers.o Sale of International Roaming SIM cards /Global Calling Cards in India: Thecards being offered to Indian Customers will be for use only outside India. However, if itis essential to activate the card for making test calls/emergent calls before the departure ofcustomer and /or after the arrival of the customer, the same shall be permitted for fortyeight (48) hours only prior to departure from India and twenty four (24) hours after arrivalin India.o Internet without Telephony: The Internet Service Provider (ISP) Policy was announcedin November, 98. ISP Licenses , which prohibit telephony on Internet ,are beingissued starting from 6.11.98 on non-exclusive basis. Three category of license existnamely A,B and C. A is all India, B is telecom Circles, Metro Districts and major districtswhere as C is SSA wide.o Internet with Telephony: Only ISP licensees are permitted, within their servicearea, to offer Internet Telephony service. The calls allowed are PC to PC in India, PC inIndia to PC/Telephone outside India, IP based calls from India to other countries.o VPN: Internet Service Providers (ISPs) can provide Virtual Private Network (VPN)Services. VPN shall be configured as Closed User Group(CUG) only and shall carry only

34

the traffic meant for the internal use of CUG and no third party traffic shall be carried onthe VPN. VPN shall not have any connectivity with PSTN / ISDN / PLMN except whenthe VPN has been set up using Internet access dial-up facility to the ISP node. Outwarddialing facility from ISP node is not permitted.o VSAT & Satellite Communication: There are two types of CUG VSAT licenses : (i)Commercial CUG VSAT license and (ii) Captive CUG VSAT license. The commercialVSAT service provider can offer the service on commercial basis to the subscribers bysetting up a number of Closed User Groups (CUGs) whereas in the captive VSATservice only one CUG can be set up for the captive use of the licensee. The scope of theservice is to provide data connectivity between various sites scattered withinterritorial boundary of India via INSAT Satellite System using Very Small ApertureTerminals (VSATs). However, these sites should form part of a Closed User Group(CUG). PSTN connectivity is not permitted.o Radio Paging: The bids for the Radio Paging Service in 27 cities were invited in 1992,the licenses were signed in 1994 and the service was commissioned in 1995. There wasa provision for a fixed license fee for first 3 years and review of the license fee afterwards.The license was for 10 years and in 2004 Govt offered a extended 10 years license withcertain license fee waivers but with the wide spread use of mobile phones, this service haslost its utility.o PMRTS: Public Mobile Radio Trunking service allows city wide connectivity throughwireless means. This service is widely used by Radio Taxi operators and companieswhose workforce is on the move and there is need to locate the present position ofemployee for best results. PSTN connectivity is permitted.o INSAT MSS: INSAT Mobile Satellite System Reporting Service (INSAT MSSReporting Service) is a one way satellite based messaging service available throughINSAT. The basic nature of this service is to provide a reporting channel via satellite to35

the group of people, who by virtue of their nature of work are operating from remotelocations without any telecom facilities and need to send short textual message or shortdata occasionally to a central station.o Voice Mail/ Audiotex/ UMS (Unified Messaging Service): Initially a seprate licensewas issued for these services. For Unified Messaging Service, transport of Voice MailMessages to other locations and subsequent retrieval by the subscriber must be on a nonrealtime basis. For providing UMS under the licence, in addition to the licence for VoiceMail/Audiotex/UMS, the licensee must also have an ISP licence. The ISP licence as wellas Voice Mail/Audiotex/ UMS licence should be for the areas proposed to be covered byUMS service. Since start of NTP-99, all access provider i.e. CMTS, UASL, Fixed serviceproviders are also allowed to provide these services as Value Added Service (VAS) undertheir license conditions.o Telemarketing: Companies intending to operate as Telemarketes need to obtain thislicense from DoT.o Other Service Provider (including BPO): As per New Telecom Policy (NTP) 1999,Other Service Providers (OSP), such as tele-banking, tele-medicine, tele-trading, ecommerce,Network Operation Centers and Vehicle Tracking Systems etc are allowed tooperate by using infrastructure provided by various access providers for non-telecomservices.Telecom Operators: Interested companies obtain license for various services to getauthorization to provide licensed telecom services in India. While hundreds of license holdersexists in India for various services, major operators are BSNL, Bharti (Airtel), Vodafone,Reliance, Aircel, Idea and Tata etc. There is a stiff competition in the market and operatorsstruggle to provide innovative services earlier than others, at rates lower than rivals,continuously find ways to extend better customer care and improve profit margins bymanaging costs. A typical diagram depicting various macro level activities performed by a

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telecom service provider is given below:In today’s fast growing customer base in telecom market, rising expectations of customers forprompt service support, very efficient & powerful software solutions are a must. For thispurpose, over the years, OSS (Operations Support Systems) & BSS (Business SupportSystems) software solutions have been developed to manage these activities. The term OSSmost frequently describes "network systems" dealing with the telecom network itself,supporting processes such as maintaining network inventory, provisioning services,configuring network components, and managing faults. Business Support Systems or BSStypically refers to "business systems" dealing with customers, supporting processes such astaking orders, processing bills, and collecting payments. The two systems together are oftenabbreviated BSS/OSS or simply B/OSS. Many proprietary software solutions are availablefrom different vendors. A standardization initiative has been taken up by TelecomManagement forum, an international membership organization of communications serviceproviders and suppliers to the communications industry. TM Forum is regarded as the mostauthoritative source for standards and frameworks in OSS. TM Forum has been active inproving a framework and discussion forum for advancements in OSS and BSS. A typicalarchitecture of OSS/BSS application is given below:Optical-OFC, DWDM etc., Transport-SDH,PDH, ATM,PSTN, DSL etc., IP-MPLS, Internet,IP TV, Multicast etc., Fixed/Wireless-PSTN, GSM, CDMA, WiMax, 3G etc., System-Windows, Unix etc.Sector Specific industry associations:The Cellular Operators Association of India (COAI) was constituted in 1995 as aregistered, non-profit, non-governmental society dedicated to the advancement ofcommunication, particularly modern communication through Cellular Mobile TelephoneServices. COAI represents Indian Cellular industry and on its behalf it interacts with thepolicy maker, the licensor, the regulator, the spectrum management agency and the industry

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(telecom /non-telecom) associations. www.coai.comKey Objectives of the COAI To improve standards and competitiveness in the Cellular Industry and attain thestatus of world class infrastructure. To facilitate affordable mobile telephony servicesfor Indians. To study the best practices & research of the industry as well as to analyse theCellular Experience worldwide. To assist relevant authorities by providing them information about the industry to helpthem formulate suitable policies for the industry's growth. To improve standards and quality of services in consultation with GSM India - theIndian chapter of the GSM Association. To maintain and upgrade services in terms of speech transmission, access, coverage,security etc, to enable expansion of cellular services. To help address problems of cellular operators relating to operational, regulatory,financial, or licensing through interaction with the Ministry of Communications & IT,Ministry of Finance, Ministry of Commerce, Department of telecommunications,Telecom Regulatory Authority of India, Financial Institutions etc.Association of Unified Telecom Service Providers of India (AUSPI) is the representativeindustry body of Unified Access Service Licensees providing CDMA & GSM MobileServices, Fixed Line Services as well as Value Added Services throughout the length andbreadth of the country. AUSPI is a registered society and works as a non-profit organizationwith the aim of delivering the promise of improved Access, Coverage and Teledensity inIndia. The objectives of the Association include collection and dissemination of knowledgeand information for promotion and healthy growth of telecom services, enunciating a telecomvision for India, fueling unprecedented domestic investment, improving teledensity andbringing value for customers. The Association interacts on policy and regulatory issues withvarious Government bodies such as the Department of Telecommunications, TelecomRegulatory Authority of India, apex industry organizations like ASSOCHAM, Confederation

38

of Indian Industry (CII) and Federation of Indian Chambers of Commerce & Industry(FICCI), technical institutions, financial analysts and other institutions of world repute. TheAssociation formulates expert opinion on industry issues and submits whenever necessary,recommendations to the concerned authorities. www.auspi.inTEMA Established in 1990, Telecom Equipment Manufacturers’ Association of India(TEMA) is recognized by the Government of India as the National Apex body to representtelecom Technology Providers, Global and Indian, Private and Government ownedcompanies. TEMA has membership of more than 150 member companies covering almost 80per cent of Indian Telecom Equipment Manufacturing. Services offered to TEMA membersinclude, interaction with Government, Policy makers, interaction with various NationalConfederations of Industries, overseas Delegations, Exhibition Organizers, MarketDevelopment Assistance Authorities, Tender Information, Excise and Customs Departments,Telecom Engineering Center for product specifications etc. Our members are exporting avariety of Telecom Equipments to South America, Middle-East, Africa, SAARC, CIS andSouth East Asian Countries. TEMA also has an Export Promotion Forum set up by theMinistry of Commerce, Government of India to promote Export of Telecom Equipments andServices. The Forum also make various recommendations to the Government for makingnecessary changes in various policies and procedures for promotion of Exports and Services.Key Industry/ Trade Associations influencing the Telecom MarketThe Confederation of Indian Industry (CII) works to create and sustain an environmentconducive to the growth of industry in India, partnering industry and government alikethrough advisory and consultative processes.CII is a non-government, not-for-profit, industryled and industry managed organisation, playing a proactive role in India's developmentprocess. Founded over 115 years ago, it is India's premier business association, with a directmembership of over 7800 organisations from the private as well as public sectors, including

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SMEs and MNCs, and an indirect membership of over 90,000 companies from around 396national and regional sectoral associations. With 64 offices in India, 9 overseas in Australia,Austria, China, France, Germany, Japan, Singapore, UK, and USA, and institutionalpartnerships with 221 counterpart organisations in 90 countries, CII serves as a referencepoint for Indian industry and the international business community. www.cii.inThe Associated Chambers of Commerce and Industry of India (ASSOCHAM), India'spremier apex chamber covers a membership of over 2 lakh companies and professionalsacross the country. It was established in 1920 by promoter chambers, representing all regionsof India. As an apex industry body, ASSOCHAM represents the interests of industry andtrade, interfaces with Government on policy issues and interacts with counterpartinternational organizations to promote bilateral economic issues. ASSOCHAM is representedon all national and local bodies and is, thus, able to pro-actively convey industry viewpoints,as also communicate and debate issues relating to public-private partnerships for economicdevelopment. www.assocham.orgFICCI: Established in 1927, FICCI is the largest and oldest apex business organisation inIndia. FICCI plays a leading role in policy debates that are at the forefront of social,economic and political change. Its publications are widely read for their in-depth research andpolicy prescriptions. FICCI works closely with the government on policy issues, enhancingefficiency, competitiveness and expanding business opportunities for industry through arange of specialised services and global linkages. It also provides a platform for sectorspecific consensus building and networking. www.ficci.comJob opportunities in Telecom SectorGovernment sector: Every year UPSC conducts Indian Engineering Services exam forrecruitment to fill up vacancies notified by various departments such as Broadcasting,Military Engineering Service, Indian Telecom Service, Indian Railways, Wireless Planningetc. Numbers of vacancies vary year to year.

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Entry level engineers with Telecom Operators: All operators recruit thousands on freshengineers every year owing to the high growth in telecom market. BSNL recruits of the orderof thousand fresh graduates every year at Junior Telecom Officer level.Sales Engineers: Many Telecom solutions are very sophisticated and technical. Such salesneed to be handled by telecom engineers.Manufacturing Sector: Most of the MNCs have set up factories in India for manufacturingtelecom network equipment as well as Customer premises equipment. There is enough jobpotential with these firms.Support jobs in Non-Telecom sector: In today’s scenario, all industries use many telecomfacilities for faster and efficient communication. All such activities require maintenanceprofessionals. Even in medical sector, growing use of telemedicine has created a new marketfor telecom professionals.Research & Development: Many MNCs have outsourced R & D in telecom to Indian firms.For example Nokia has outsourced its product design to M/s TCS. All such deals create jobopportunities for telecom engineers.IT sector: The core of BPO sector is the telecom network. IT sectors generates huge telecomjobs.Education sector: Government of India’s mission mode project on Education such as Sarvashiksha Abhiyan, connecting all libraries in India, providing broadband to all schools etc.requires telecom professionals to install and manage this huge network.National E-Governance Project: The ambitions plan of India to network each nook &corner of the country and provide a citizen centric, single window service counter requirescreation of vast telecom network across the country. Each State is implementing State WideArea Network (SWAN). All such projects create demand for telecom professionals.Research executives with Consultancy Firms: Telecom growth impacts a country’s economy.Many consultancy firms thrive on generating reports on business models, future potential and

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extending guidance to existing and new entrants in telecom market. There is a significantneed for telecom professionals with such firms also.Pay range: Entry level engineer can get a starting annual package ranging from 2-4 lakhdepending on the nature of job & employer firm.

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