Monday, June 8, 2009

BTCL Services - Prospects & Possibilities

M. A. Moonem, (Asstt. Divisional Engineer, BTCL)

Bangladesh Telecommunications Company Limited (BTCL) has been the pioneer in telecommunication sector in Bangladesh. It started in 1947 as Pakistan Post & Telegraph Department under Telegraph Act - 1885 and in 1975 the corporate body of Bangladesh Telegraph & Telephone Board (BTTB) had been formed by T&T Board Ordinance - 1975. In 2008 BTCL was formed as a Govt. owned company by the T&T Board (amendment) Ordinance - 2008. From the very first basic analog telephony system BTCL has walked a long way towards its present stage of modern versatile data and telecommunication service. At times BTCL was the only telecom operator and service provider in our country. Due to rapid technological advancement, change in subscriber’s demand and penetration of many telecom operators and related service providers BTCL now has to face fierce competition to establish its dominance in present telecom market. As a junior member in BTCL family I just wish to express my simple understanding and opinion about our overall products and services.

Basic Voice Telephony:

Presently BTCL has about 1 million PSTN (Public Switched Telephone Network) or fixed telephone subscribers across the country, where the total number of telephone (both mobile and PSTN) subscribers are around 45 millions in Bangladesh. Growth rate of fixed telephone subscribers in recent years is also negligible in comparison to that of mobile subscribers. Mobile phones are getting popular due to its wireless handy mobility and its capability of integrating various value added services along with basic voice telephony service. As a newer versatile technology cellular telecommunication has acquired a huge market share of telecom subscribers all over the world. But world leaders in telecom market throughout the world think that PSTN network has huge possibilities just if addition of newer technologies, services and changing trend to data communication is possible.

Now BTCL has about 730 exchanges, 18 TAX (Trunk Auto Exchange), 3 Satellite Earth Stations, 6 ITX (International Trunk Exchange) and countrywide microwave and optical fiber network to provide service to its valued subscribers. BTCL offers the lowest rate (only 10 paisa/min) for local calls and it also lowered connection & other telephone related fees to very cheap. This is obvious that we must pay effort now to increase number of subscribers to make BTCL efficient and as well as profitable in such a competitive market. Subscribers at Dhaka, Chittagong and some other district-cities have demand for BTCL fixed telephone most. There are some places in Dhaka where there is a good demand for BTCL fixed phone, but due to number shortage or insufficient cable-pair in the demanding area, sometimes we cannot provide new connections to them. Moreover underground telephone cables are getting cut-off very often disrupting service and the cable network is expensive to install and maintain also. In such cases BTCL may step towards CDMA WLL solution in parallel to existing wired connections as some other PSTN operators are running.

Data & Internet:

Now more than 33,000 subscribers from 64 districts and 402 upazillas / growth centers having digital exchanges are using BTCL dialup internet. BTCL’s premium dialup service (user: btcl, password: btcl, dial no: 0101234) from all around the country became so popular a service that we are in need of expanding its capacity to provide this service. In 2007-08 FY BTCL earned Tk. 64.1 crore from Internet, Leased line, DDN, Domain service etc. Now we have around 1900 km of optical fiber network and a vast microwave network connecting almost all the districts. It is an opportunity for BTCL to meet up the rising demand for high speed data and internet service throughout the country. People may please visit the website for data & internet for relevant information.


BTCL is going to introduce ADSL (Asymmetric Digital Subscriber Line) service in 12 districts; Dhaka, Narayanganj, Gazipur, Chittagong, Comilla, Barisal, Rajshahi, Mymensingh, Sylhet, Bogra, Khulna, Jessore. ADSL is a form of DSL, a data communication technology that enables faster data transmission over copper telephone lines than a conventional voice-band modem can provide. It does this by utilizing frequencies that are not used by a voice telephone call. A splitter or filter allows a single telephone connection to be used for both ADSL service and voice calls at the same time.

Figure: A schematic of typical ADSL connection.

At the telephone exchange the line terminates at a DSLAM (DSL Access Module) where another frequency splitter separates the voice band for the conventional phone network. Data carried by the ADSL is routed over BTCL’s data network and data don’t go through the local exchange’s PCM process. We are expecting a good response from our subscribers as we hope to meet up their demand for truly broadband access to internet.


BTCL has another new element in its network, NGN (Next Generation Network). We have the core part installed in Mogbazar TAX (Trunk Auto Exchange) and four media gateways at Sylhet, Kustia, Khulna and Barisal. Future PSTN network may be of NGN type because of its adaptability to upcoming packet-based data, voice and various intelligent services.

Figure: NGN capability of accommodating different new services.

NGN is actually a packet-based network able to provide telecommunication services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It offers unfettered access by users to different service providers. BTCL may think of expanding NGN and get new features to provide services like IPTV, triple-play, IP Phone and other multimedia services to provide to end users.

I N Services:

BTCL installed a Fixed Intelligent Network (FIN) Platform at Mogbazar with 3 (three) services as (1) Prepaid Calling Card (PCC) service, (2) Prepaid Telephone (PPT) Service and (3) Free Phone / Toll-free Service (FPS). Its Commercial operation started on 17th July, 2006 through the PCC service. Using this service people can make ISD, E-ISD, NWD calls from anywhere within the country using BTCL prepaid scratch cards which are available at Post Offices, City Bank, Dhaka Bank branches countrywide and Basic Bank bill booths in Dhaka. It drew good customer attention and people are using this service from more than 60 different locations in the country. We need to take an appropriate marketing strategy to make these calling cards available to the demanding subscribers.

Figure: User connectivity to the BTCL FIN system.

Prepaid telephone (PPT) service had been launched in 1st April, 2008. In this service a PPT subscriber’s all outgoing calls must go through IN Platform and call charge shall be deducted from the PPT account that can be recharged with the same BTCL prepaid calling card.

Free Phone Service (FPS
) or toll-free service is now ready to be served. Business communities, corporate bodies may provide call-center services through FPS. Here a service subscriber shall have a toll-free access code like 0800-217-XXX and people dialing to this number shall not be charged rather the called party shall pay for the call. This may be a good business promotion tool.

Future IN services: BTCL existing IN Platform is physically capable of providing many more attractive intelligent services and features that can add to our revenue growth. BTCL has to buy licenses and install those services in IN platform. Some popular IN services that our neighboring countries like India, Pakistan have already running successfully are as follows:

Premium Rate Service (PRM): With PRM service, the operator can host content service (like news or other contents) offered by the content service provider and charge a premium fee for the content access.

Mass Calling Service (MCS): This service has attractive features like arrangement of interactive Question-Answer or Lucky Draw event, ordering for some goods via IVR, tele-voting, collect donations or playing games etc.

Utility Bill Pay service (UBP): UBP service provides the service users with the function of paying for the utility bills with prepaid scratch cards. After the service user buys a card issued by the service provider, he/she can dial the UBP access code provided by the service provider to enter the telephone flow, and then complete the bill payment according to the voice announcements played by the system. Now GrameenPhone is collecting gas & electricity bills using such services. BTCL primarily may introduce UBP service only for bill payment of BTCL’s post-paid subscribers which may greatly save human & material resources and save users from hassle of queuing to pay the bill.

Now BTCL has only one SSP (Service Switching Point) connected with the IN system. If we can just install some more SSPs in major divisional cities and buy new IN services, subscribers all over the country shall get access to all IN services and features easily.


For BTCL, marketing of its product and services appears as a new concept since former BTTB had a few activities regarding this. Now a day it is hard to survive in competition without proper marketing strategy. BTCL needs first to advertise to prospective customers about what services and products we have, and then to try to make them available to users and continuously analyze market trend and take necessary steps accordingly. BTCL, of course, has formed a marketing department for this purpose.


BTCL has one Telecom Staff College at Gazipur, 3 Telecom Training Centers at Tejgaon, Khulna & Bogra and 5 Sub-centers at Dhaka, Jessore, Barisal, Chittagong and Rajshahi to train up its staffs and officers. Our training infrastructures need to be upgraded and these centers may be a source of earning revenue also.


As a new ‘company’ in telecommunication sector BTCL should play a dynamic role to strengthen its existence and come up with a new face. To do so BTCL needs to go through proper planning & implementation, wise investment and efficient operation at relevant spheres of its functionality. BTCL should participate in the market with a view to make profit as well as serving our people satisfactorily. Whatever the change in technology or market-trend comes we hope BTCL will remain on top as it has been for decades in Bangladesh. (Teletech 2009)

Saturday, June 6, 2009

Traffic Congestion

Md. Habibur Rahman
Director, BTTB

What is Traffic :
Any type of load imposed on a system which is supposed to be carried by the system is defined as the traffic. For example, Road traffic, Railway traffic, Telephone traffic etc. In an office number of files given to a clerk for disposal is also a kind of traffic. In telecommunication, voice, data and images in the form of electrical signal which is to be transferred from one telecom equipment to another telecom equipment through telecom network is defined as telecom traffic.

Traffic Congestion in telecommunication network:
It is defined as "The condition of a network where the immediate establishment of a new connection is impossible owing to the unavailability of network element". It may happen momentarily for an unusually high traffic. Accumulation of traffic in any portion of network is the traffic congestion.
Behavior of Telephone Subscriber:
Only a small portion of subscribers will be using their telephones at any time, even during busiest hour. The probability of a subscriber to make a call is completely uncertain. But the system is made always ready for a response to the subscriber.

The nature of telephone traffic:
It is so uncertain that some times a huge number of calls are accumulated. Either calls are lost or held in que and some times there is no call so that a portion of network remains idle.
Tele-Traffic Engineering And Traffic Congestion:
The object of Tele-traffic Engineering is to formulate a set of procedure for the design and day to
day management of a telecom system that will result in the most economic provision of telecom
switching equipment and trunk circuits subject to providing a satisfactory service at an
acceptable cost to the users of the system Traffic congestion is a big problem to engineer for
designing equipment it is I to provide sufficient equipment to permit the subscribers
simultaneously to be on calls but practically it is not require

Telecommunication Administration & Traffic Congestion:
Telephone network are so designed that the limit to the simultaneous calls they can ha is the telecom administration who decides w limit be. As the demand of the subscribe unpredictable, traffic calculation for de; equipment made on the basis of assumption theme of the administration is to give uninterrupted service to the subscriber though an unusually high traffic may be generated by the subscribe a very short time, it is not economic to design a network which will overcome a very high for a very short time. Dimensioning of equipment is made on the basis of average traffic on bus and not on the basis of peak traffic.

Measurement of Traffic:
I. Generally the traffic carried by the cc control equipment like Processor, Memory Registers etc. are measured by considering occupancy of the equipment.
Line circuit, Trunk circuit, DTI and peripheral equipment are scanned periodically and from the Busy/Idle status counted from scanned result the traffic carried by the equipment is calculated.
Traffic Congestion are of two types:
1. Time congestion The ratio of time for congestion exists to the total time cons; for measurement. It is an estimate of the ability that an external observer will fin system in a state of congestion.
Call Congestion The ratio of number of call attempts which can not be matured immediately to the total number of call attempts.

Causes of traffic congestion
The congestion occurs for various reasons depending on switch facilities, Exchange equipment and transmission link. Traffic congestion mainly occurs due to inadequate capacity of equipment and improper network management. Causes of Congestion may be classified as follow
I. Congestion due to faulty equipment.
2. Congestion due to generation of high traffic.
3. Congestion due to improper configuration of network.

Congestion due to faulty equipment:
Faulty equipment refuse to carry traffic. The load is transferred to working equipment. When a switching system failed to process a call, the subscriber try again and again. As a result traffic increases and congestion occurs. Moreover, a faulty equipment faces congestion more than that of a good one. Failure of a transmission equipment may cause congestion to the switching equipment as the traffic stored in the memory of the stored program controlled switching system is increased.

Congestion due to generation of high traffic:
A sudden increase in the originating and terminationg call can cause traffic congestion. The traffic may be increased in a particular area due to
1. Natural disaster (Flood, Cyclone, Earth-quake, Fire-hazards, Accident etc.)
2. Unusual manmade situation (Accidental explosion, Mass agitation, Strike, Political gathering, Failure of Electric Supply system.).
3. Seasonal factor (Eid, Puja, X-Mas day, Summer, Winter & other Vacations)
4. Other activities (Recreational Programs in Radio and Television Broadcasting system, Death of a renowned person, Distance Education & Healthcare etc.)
Congestion due to improper configuration of Networks:
Sometimes it appears congestion in a portion of network while there exist idle equipment in
another portion of network. Particularly in transmission links, one link may be in congestion while another link remains idle. In this case overflow traffic from one link may be transmitted through alternate link via transit to another node. Due to failure of one link, the traffic may be re-routed to another link and causes congestion to that link.
Traffic Congestion Relieving Procedure:
1. Detect the occurrence of traffic congestion.
2. Analyze and find the location, portion of equipment which is under congestion and cause of congestion.
3. Each portion of network where there is no congestion should be informed the occurrence of congestion. So that preventive measure may be taken.
4. Determine the command and restriction grade to be used for automatic traffic control according to the status of congestion.
5. Start restriction at the originating and transit offices, so that congestion in one station can not influence other station.
6. Start restriction at the terminating offices if other restriction proves insufficient.
7. Release restriction as congestion subsides.
Traffic Control
With the increase in the occupancy of the equipment, traffic is restricted so that congestion can not cause the failure of equipment. In this case either the traffic loss is allowed or a mechanism of delaying the traffic is introduced.
Effect of Traffic congestion on Revenue:
Due to traffic congestion a large volume of traffic is lost or delayed. The equipment may be failed to work. Subscribers become unhappy as they are not getting the service. Less revenue will be earned.

Traffic Congestion is a problem appeared at random. It is also increasing day by day in every sphere of life. Our objective is to overcome the problem efficiently, effectively and economically. Congestion may be minimized through expert planning, proper dimensioning and efficient management of network.

International Call Termination

Md. Ahsan-ul Islam

With the advent of new technology illegal international call termination is mushrooming in Bangladesh. Thousands of illegal call terminators are active in the big cities where ISP (Internet Service Provider) connectivity is available and it is incrementing every day. As a result Government is loosing valuable foreign currency.

The simple meaning of international call termination is carrying international voice traffic from around the world and delivering those to the desired telephone numbers. As such the call terminators are acting as international backbone (long distance) operator violating existing rules and regulations.

The call termination technique has become so simple that anybody having few telephone numbers and a broad band ISP connectivity can launch the service. The step by step scenario is:

Ø The call originated from the partner VOIP carrier worldwide is routed over the IP network with a particular IP address.

Ø The call comes as IP packets to the particular ISP provider. The ISP provider sends the packets to the call terminator who is having broadband Internet connectivity with unique IP address.

Ø International call terminator receives the IP packets in its Gateway. The Gateway is connected with ISP by broadband connectivity of Symmetrical Bandwidth. The gateways have provision for 4, 8, 16 or more telephone lines.

Ø International calls are unbundled from VOIP to telephone calls in the call terminators gateway and terminated via above telephone lines to the called party.

In brief call Termination Business requires the following :

Ø VOIP Gateway with Analog (4, 8, 16, etc.) ports.

Ø VOIP billing server to account the paid minutes.

Ø Telephone Number at least 4 (four).

Ø Broadband Internet Access with Symmetric Bandwidth with 8-10 kbps/ Voice- Channel.

Ø Partnership with a VOIP Carrier.

The digital VOIP-based termination solution is also available. But it is not in use largely. This type of termination utilizes single to multiple E1(30 channel) connections. The generally used brand for these Gateways are Cisco, Quintum, Multitech etc.
In the early days of call termination, managed IP networks were used. But with the coming up of newer technology and high capacity submarine cable, Public Internet is being used for call termination now a days.
If we look into the history of illegal call termination in Bangladesh it can be said that the evil clutch started to spread from the year 2000. When the Government has opened the use of V-SAT to flourish information technology (IT). Taking this advantage some V-SAT users started illegal call termination business.

The effect of call termination is alarming. International calls via BTTB Gateway(ITX) is decreasing day by day resulting huge loss of foreign currency. On the other hand, it is severely affecting the performance of telephone switching equipment. As the holding time for call termination is too high and telephone number is not a standard tool for call delivery, such high usage is not considered in telephone exchange dimensioning. So, PSTN subscribers are facing congestion problem in subscriber stage. Moreover due to pilling up of telephone numbers by the call terminators the real subscribers are being deprived of getting telephone lines. In the case of Mobile the congestion scenario is also acute. Due to use of Mobile numbers for call termination the mobile subscribers of the specific cells find difficulty in getting radio access channel for generating or receiving calls.

It is high time to decide on this illegal practice. Otherwise the Government will be deprived from huge amount of foreign currency every year. On the other hand everyday more and more telephone numbers will go to the hand of call terminators and the people who really needs telephone will not get it. Concurrently the quality of service of telephone exchange will decrease remarkably in the days to come. In this context, Government should take immediate step to stop illegal voice termination for the betterment of the country.

Telecommunications Network Planning in A Multi-Operator Environment

A. H. M. Shafiqul Islam.Director. BTTB

1. Key elements of Network Planning

• Data collection and supervision of the network to determine its status.
• Forecasting of number of subscribers, traffic and traffic interest per subscriber.
• Total traffic showing in traffic matrices.
• Fundamental technical planning.
• Dimensioning of the network
• Financial analysis.
Net work planning in a turbulent environment (multi operator & multi service) requires additional decision data. The following areas are affected
• The market, what will be the operators future role in a market exposed to severe competition.
• Customer demands diversification; diversified customer demand with services like Internet, multimedia, entertainment services and mobility etc. must be taken into account.
• Changes in technology, new technologies like ATM (Asynchronous Transfer Mode), IPPSTN (Internet Protocol Public Switched Telephone Network) and further development of existing technology may require attention.
• Standard, new standard are issued continuously.
• Pricing & cost analysis, wide fluctuations of pricing and costing in different parts of the network may be happened due to utilization of alternative technology, routes and operator etc.

2. Evolution of Network configuration Bangladesh in 1999 and 2002

The total capacity of 627 telephone exchanges is 474,322 lines. Telephone exchanges are of different type like digital, analog and manual. Long distance transmission system are based on radio links out of which very few are with digital PDH radio.
By the year 2002 another 467,450 digital telephone lines will be added in the country. out of which 310,150 lines will be expansion and 157,300 lines will be replacement. By year 2002 all district towns will have digital telephone exchanges interconnecting among themselves by digital transmission links (OFC or radio) TAX I sub-TAX will be added at 11 more cities/towns giving opportunities to increase P01 (point of interconnection) with private operators.
BTTB is major telecom operator in the country. Two (2) numbers private operators are working as rural telephone operator and four (4) number private operators are working as cellular mobile operator. The provision for P01 (Point of Interconnection) between BTTB and private operators are kept at ITX, TAX and Tandem exchanges. List of cities/towns along with number of POIs as in 1999 and as envisaged in 2002 are shown in the next table.

Besides these there will he PCI (TAX) at Barisal, Comilla, Kushtia, Myrnensingh, Rangamati, Noakhali, Faridpur, Jessore, Dinajpur, Rangpur & Pabna by the year 2002. At present total P01 (ITX) = 3 and PCI (TAX) = 9, which will he PCI (ITX)= 2, POT (TAX)=
21 and tandem= 3 by the year 2002.
Requirement of Changes in Fundamental Technical planning (FTP)

3.1 Numbering Plan

3.1.1 Present status. First digits of national significant numbers in use are.
First digit - 1. mobile service (presently 11, 17, 18, 19 are allocated)
First digit-2 to 9, are allocated for geographical services for Dhaka, Chittagong, Khulna, Bogra, Southern Dhaka, Rajshahi, Sylhet and Mymensingh. Therefore no first digit of national significant number is left free for introduction of any major new service or new operator etc.
Geographical area codes are varied from one to four digits and local numbers from three to seven digits.
Rural operators are sharing the same geographical codes with BTTB.
First digit of Dhaka City exchange code are now 2, 3, 4, 5, 6, 7, 8 and 9. Hence there is little opportunity to allocate exchange code for a new incumbent telecom operator in Dhaka. Utilization of 7 digit codes of Dl city is very poor

3.1.2 Future proposition. Some measures can taken by clearing few first national significant digits from use of geographical identification in order to keep them free for cautiously use non-geographic service is in future. BTTB and Rural telephone operator will careful about choosing first digit of individual exchange codes. After closing all analog exchanges in Dl few first digits of existing exchange number will be free, those are 2, 3,4, 5, and 6. TI should be kept free to use as access codes new IN (Intelligent Network) services to be introduced in future.

3.2 Transmission Plan

3.2.1 Present status. Existing national transmission systems are analog and digital I radio systems. Transmission plans are a’ able accordingly.

3.2.2 Future proposition. After year 2002 national transmission systems covering all district towns will be on SDH multiplexing on cal fiber link and digital microwave (SDI PDH) links, Bandwidth will be high, suit to band width bearing capacity of the pre days demand for multimedia services multi operator environment. New transmission plan will be set up to meet the new criteria of services.

3.3 Routing Plan

3.3.1 Present status. Exiting national transmission networks are on star format, having limited bandwidth. Therefore, limited seal alternative routing provisions are now a’ able, which causes lesser reliability. multi operator environment sometime it happens that one operator blames the other for not availing service reliability.

3.3.2 Future proposition. Future national transmission network will have wider band width, and it will form few rings in northern and southern part of the country, more over number of TAX/sub TAX will also increase. Therefore, after the year 2002, provisions for more alternative routing could be kept in order to obtain better service reliability.

3.4 Signaling Plan.

3.4.1 Present Status. Existing national signaling systems are now done by R2 and CCS7. For international service it is CAS 5. Different telecom operators are connected with BTTB with R2 and C7. National signaling plans has not so far been established in detail.
3.4.2 Future proposition. After the year 2002, the national network will mostly be converted to digital and at that time signaling system will also mostly be CCS7. It would be necessary to set up a national, signaling plan before the country’s signaling network become more complex in the multi operator environment. BTTB has a plan to install STP (Signal Transfer Point) to ease the handling of complex signaling network.

3.5 Charging Plan.

3.5.1 Present status. BTTB has a charging plan, stipulating for what subscribers should pay for, how much they should pay, and the basis for charging.

3.5.2 Future proposition. In future service offering by BTTB can be wholly or partly exposed to fierce competition. Moreover in the multi operator environment inter operator revenue/tariff-sharing matter has come as a part of charging plan. Regarding inter operator billing & revenue collection there should be provisions of bulk billing. Further to that, the billing system may be based on individual calls or based on average traffic profile. In the case of average traffic profile, the billing may be based on representative traffic observation carried out periodically. Periodicity depends on the basis of changes of traffic profile. For the fast changing traffic profile, frequent measurement is required, usually once in six months.

3.6 Frequency plan.

3.6.1 Present status. Frequency planning was earlier a part of BTTB’s responsibility. It is now under the Ministry of Posts and telecommunication (MOPT) responsibility until the formation of TRC (Telecom Regulatory Commission).

3.6.2 Future Proposition. Frequency utilization is increasing day by day for new competitive services of cellular Mobile service, WLL (Wireless Local Loop) service etc. As there are four mobile operators, therefore use of frequency has become quadruplicated,
where as there is scarcity of availability offrequency.

4. Conclusion

Following recommendations for BTTB may be considered necessary to ensure good
network planning in a multi operator environment
• There should be precise data base related to statistical, traffic, technical, pricing and costmanagement.
• There should be a good set up in planning wing for traffic engineering and fundamentaltechnical planning.
• There should be modern cost management set up in BTTB.
• There should be a permanent BTTB liaison office for co-ordination with private telecommunication operators.

(Published: May 2000)I

Bangladesh entering into a Consortium Submarine Cable

Md. Monwar Hossain
GM/PD, Submarine Cable Project. BTTB (2003)

1. History of Submarine Cable :

Anybody dealing with Telecommunication will be curious to know as to when the first Submarine cable was laid. It is for their information that TAT-1 was the first trans-Atlantic telephone cable, which was laid in 1956. It was a coaxial cable catering for four thousand voice circuits but coaxial cable with it repeaters was running with technological limitations. So fiber optics Submarine cable brought forth the new solution overcoming the technological difficulties. In 1983 TAT-8 was the first optical fiber cable, which contained two pairs of single mode fibers carrying 35 thousand telephone circuits across the Atlantic.

2. Shark biting the fiber optic cable

[AT&T’s] Submarine Systems division carefully planned another test of TAT-8 technology in the Canary Islands of Africa, where the Spanish telephone authority wanted a link between Grand Canary and Tenerife Islands.

Sharks had ignored coaxial cables. Why should they turn their razor-sharp teeth on fiber. [It turned out] the electric field from the current attracted the predators, who apparently use it in hunting. Coaxial cable also carried a current, but its outer metal wrap blocked the electric field from reaching into the water. Nothing blocked the field from reaching the water around the fiber cable, where the sharks could sense it. Hence Engineers had to provide protection on FOC Submarine cable against shark biting.

3. Bangladesh efforts to be connected to Submarine Cable

Bangladesh T&T Board first prepared a project concept paper on 12th Jan 1998 regarding a Submarine Cable project. Bangladesh was making efforts to join (a) SEA-ME-WE-3, (b) SAFE and (c) Oxygen, three Submarine Cables materializing almost in similar time span.

On 4th Oct 2000, ECNEC approved a project namely “Establishment of International connectivity through Submarine Cable System” and the total project cost was 921.18 cr. BTTB invited International tender on 16th Aug 2001 for this project. After evaluation the case was sent to the Ministry for further process in the Inter-Ministerial committee.

It was at that stage while 3 (three) inter-Ministerial meetings were held to discuss the bids, Bangladesh received the first invitation to join a Consortium Cable.

4. The Consortium Cable, SEA-ME-WE-4

This cable covers South-East Asia, Middle East, Western Europe-4, starting from Singapore to France. The total length of the consortium cable will be about 21000km and 14 parties have shown interest and singed the Memorandum of Understanding (MOU) to develop a consortium FOC cable.

The following are the 14 Potential Initial Parties (PIP’s) who signed the MOU on 4th Sept 2002 in Bali of Indonesia;

Indosat (Indonesia)
Telecom Malaysia (Malaysia)
SingTel (Singapore)
Bharati (India)
VSNL (India)
BTTB (Bangladesh)
STL (Srilanka Telecom Ltd)
Etisalat (UAE)
STC (Saudi Telecom Corporation)
World com (England)
TE (Telecom Egypt)
TI (Telecom Italia)
PTCL (Pakistan Telecom Co. Ltd)
FT (French Telecom).

There have been already 7 meetings of the consortium in various member countries. Tender Documents for the FOC cable are almost ready and it is expected to sign the Suppliers contract by Nov 2003.

For Bangladesh the landing station will be at Cox’s Bazar and therefore BTTB has to develop a FOC link between Cox’s Bazar and Chittagong.

Two more new landing parties have been considered for inclusion in the Consortium, they are;

CAT - Thailand.
Tunisie Telecom - Tunisia.
Few non-landing parties are also under consideration of the Management Committee for inclusion in the consortium.

The minimum Investment level in this Consortium Cable has been 30 million USD. Normally for the Branching parties, each party has to spend for its own branch cost (50 million USD for Bangladesh branch, 1240 Km) and 15 m USD should be the contribution towards the express way. It is worth mentioning here that the total route will have 2 fiber pairs (One pair for branches and one pair will touch the full landing stations only). The total project in expected to be completed by 1st quarter of 2005.

5. System Configuration :

Total four segment , namely segment 1, 2,3 & 4 will be constructed in SMW4 consortium cable that will run from Tuas ( Singapore ) to Marseilles ( France ). The details of the segments are :

Segment 1 :
Segment 1a shall contain two fibre pairs where one fibre pair is directly connected between Tuas (Singapore) and Chennai (India) and the other fibre pair is connected between Tuas and Chennai with branches to Melaka (Malaysia), Medan (Indonesia), Satun ( Thailand ) and Cox’s Bazar (Bangladesh) .

Segment 1b shall contain two fibre pairs where one fibre pair is directly connected between Channai and Mumbai and other fibre pair is connected between Channai and Mumbai with a branch to Colombo.

Segment 2 :
Segment 2a shall contain two fibre pairs one fibre pair is directly connected to Mumbai and Jeddah and other pair is connected to Mumbai and Jeddah with branches to Karachi (Pakistan) and Fajairah (UAE).

Segment 2b shall contain two fiber pairs where both pair are directly connected between Jeddah and Suez(Egypt).

Segment 3 :
Two fibre pairs will run through Suez, Cairo and Alexandria. This a land Cable
( Terrestrial Segment ).

Segment 4 :
Segment 4 shall contain two fibre pairs where one fibre pair is directly connected between Alexandria and Marseilles (France) and the other fibre pair is connected between Alexandria and Marseilles with branches to Palermo (Italy) and Bizerte ( Tunisia ).

A route diagram of the cable is annexed with this article as annex – 1.

6. Capacity :

1) Using WDM ( Wave Division Multiplexing ) technology with a design capacity of at least 64x10 Gbit/s transmission per fibre pair ( FP ).For two FPs it will be 1.28 Tbit/sec.
In WDM system 64 wave length (λ) can be transmitted through one FP and 10 Gbit/sec for each wave length ( λ ).

2) Initially it will start with 8x10 Gbit/sec on each fibre pair (FP) and capable of being equipped in multiples of 8 x 10 Gbit/sec per FP.

7. Advantage for Bangladesh to join a Consortium Submarine Cable rather than having its own Submarine Cable

(a) Bangladesh will get an initial capacity of 10Gbps, which will cater for next few years. Any additional capacity can be procured through some incremental payment to the Consortium and the capacity can be enhanced up to 100 Gbit/s.

(b) The operation and maintenance of the Submarine Consortium cable will be the full responsibility of the Consortium and it would be cheaper for Bangladesh. On the contrary, if Bangladesh possesses its own Submarine cable, she has to sign another operation and maintenance agreement with a third party and this agreement will be definitely costly. Bangladesh neither has the skill manpower or equipment/ship for operation and maintenance of the Submarine cable nor does it have any experience since this Consortium cable will be the first Submarine cable in the country.

(c) Bangladesh will get free landing entry into the 12 member countries and bilateral traffic can be sent through half circuit basis.

(d) The project cost in the Consortium will be much cheaper than Bangladesh having its own Submarine Cable.

(e) This Consortium cable will provide us with sufficient bandwidth for ICT expansion and software export/data transmission at a much cheaper rate. Bangladesh having a Submarine cable connectivity internationally will open up a new era of communication which will not only encourage telecommunication at a cheaper rate (no delay in communication, less noisy, faster and smoother seamless communication can be achieved) but also will have enormous opportunities in respect of software export, data entry, call centers etc in order to earn foreign currency.

Thursday, June 4, 2009

Should We Start 3G?

Md. Habibur Rahman


World Mobile market even after full maturity of 2.0G/2.5G technology is still striving to migrate to Third Generation. Second Generation which was supposed to be obsolete by this time, today still acquires 85% of the market share. 3G after 8 years (since 2001) of start acquires only 15% market share. 3GPP before significant deployment of WCDMA based 3G declares the OFDMA based new standard LTE. 3GPP in line technologies UMTS, HSDPA, HSPA, HSPA+ has not bothered for logical gap to offer for deployment. When critics are still asking about the success of 3G, declaration of LTE puts the situation yet complex. This is off course the investment challenge for the mobile operators. Though vendors are very much optimistic about benefit of entering earlier in 3G chains and promising about smooth migration to upward technology by software up gradation only, countries like Bangladesh are to think twice to enter in such non returning vessel. Every vendor has astringent experience about software up gradation of the proprietary system.
It is Mobile WiMAX that compels 3GPP to develop LTE. Vendors deliberately declare LTE roadmap ahead of time to defend against Mobile WiMAX. At this instant LTE is the choice more to the leading CDMA operators in USA to deploy quickly because of the bottleneck of CDMA to higher data rate. WCDMA operators are little pessimistic about quick LTE.
Despite my own attachment with a mobile operator, the insight in the article is from my personal viewpoint.

History of Mobile Generations

Initial mobile

Though first mobile communication was launched in 1946 in USA, the development of mobile technology was stagnant till late 70’s due to technological constraint. The tremendous development of semi conductor technology during this period and subsequent innovation of microprocessors in 1975 helped mobile to breakthrough commercially. Till further development of cellular technology, capacity problem was the key constraint of commercial mobile. In 1978 total number of mobile (only in USA) was no above 10,000. Mobile technology upto this is termed as 0 Generation Mobile.

Cellular Mobile
A quantum leap in mobile communication occurred in 1979 after introduction of cellular mobile & came outside US, first in Japan. This cellular mobile is termed as 1st Generation mobile. The total number of 1G mobile in 1992 reached to 10 million. Though the core network of 1G was digital, the analogue radio network limited the capacity of 1st Generation mobile.
2G Mobile

Digitalization of the radio network was another quantum leap in mobile history & is termed as 2nd Generation Mobile, started in 1992. GSM, the European 2G mobile is the most successful standard which beat the legacy US mobile standard & captured the whole world soon, even in the territory of US. The developed standards for 2G mobile are-

GSM : Europe, Asia, Australia, South , America etc.
DAMPS : America, Australia etc.
PDS : Japan
IS-95 : America, Korea, Japan, China etc

In 2001 the total number of 2G mobile was 660 million where only GSM is 410 million.

Third Generation Mobile 3G

3G vision

Third Generation mobile is the first ITU intervention in mobile technology through a platform named IMT2000. From the past bitter experience of multi standards as well as tremendous success of GSM as a regional standard entrusted the mobile community
toward a common standard for the welfare of the future world. This common standard is termed as 3G. The IMT2000 as the name implies target 3G deployment by 2000 and use frequency of 2000 MHz range.

One objective of 3G mobile is broadband internet access through mobile PC. Internet is the “Global Town Square” where people can meet, chat & blog. The data rate of 3G was aimed up to 2 Mbps. Video phone, mobile commerce, Telemedicine, distant education is the committed service of 3G. Worldwide compatibility & mobility, Home PLMN (HPLMN) service outside geographical border are also the goal of 3G.
With above objectives, 3G technologies under the umbrella of IMT2000 targeted to replace 2G legacy network sooner as possible. As an initial hype of 3G the developed countries started auction 3G spectrum. Initially UK sold 3G spectrum by auction at USD 35.5 billion & Germany at USD 46 billion. Economic down train of Telecom Industry in 2001 stopped 3G auction. Despite this 4 Asian Tiger deployed 3G very shortly. The first 3G mobile standard (FOMA) was launched in 2001 in Japan.

3G Technology Roadmap

The key technology of 3G is CDMA/WCDMA. WCDMA based 3G mobile standard has different version like UMTS, HSDPA, HSPA,HSPA+ and CDMA based 3G standard is CDMA2000 with versions CDMA2000 1X, 1xEV-DO Rel.0 & 1xEV-DO Rev. A. OFDMA based LTE termed as 3G & beyond (also termed as 4G) aims to provide extra high data rate of more than 100 Mbps. LTE is designed with reduced latency (10 milliseconds) to allow VoIP through the data network & consequently deploy all IP network up to the user terminal.

3G market share

Year :: Total Mobile :: Total Growth :: Total 3G :: 3G %
2006 :: 2613 :: 28% :: 166 :: 6%
2007 :: 3250 :: 25% :: 311 :: 9%
2008 :: 3907 :: 20% :: 506 :: 13%
2009 expect :: 4441 :: 11% :: 750 :: 17%
In December 2008, the total number of 2G/2.5G/3G mobile is 3907 million where 3G mobile is 506 million which is 13% only of total mobile. In December 2009 total mobile is expected 4441 where 17% 3G is assumed. This is an indication about dominancy of 2.5G over 3G still after long time of deployment.

3G Challenges

As the interim standard (GPRS/EDGE) could at least cater people’s demand of voice & data and there is little difference between 2g & 3G services, the core marketing concept of product differentiation could not cross threshold margin to succeed 3G over 2/2.5G. Along with these factors the economic downturn in the Telecom industry ultimately slowed down the 3G implementations except in few advanced countries like Japan, Korea, UK, Australia, Austria, Singapore etc. Many operators of the world and especially in the third world countries including Asia Pacific were asleep on the subject of 3G till recent past.

After implementing 3G UMTS in few countries different protocols like HSDPA, HSUPA, HSPA was developed with several megabytes data rates (up to 14.4 Mbps). This development was remarkable in the history of mobile broadband. During initial adoption of 3G, such quick technological up gradation leads the mobile operators ‘Wait & See’ to save CAPEX.

Besides these challenges, WiMAX is another factor that leads 3G to further back footage. IEEE.802.16e standard Mobile WiMAX with a commitment of 75 Mbps data rate (with mobility) create vibrant in 3G roadmap. Intel the leader of computer chip vendor, being the producer of WiMAX chipsets tried to enter Qualcom’s legacy mobile market aggressively.

Japanese has pioneered the mobile commerce ahead of US & Europe by the advent of 3G. If we examine what the Japanese are buying, we will realize that they are not far ahead of the rest of the world. They are buying predominantly Screen server & Ring tones. Small screen & low resolution of mobile is also the challenge of mobile commerce.

Video phone is not as popular as it is expected because of people’s habituation to keep handset on the ear not in front of eye.

3G Jargon

3GPP :Third Generation Partnership Project
CDMA : Code Division Multiple Access
WCDMA : Wideband CDMA
OFDMA : Orthogonal FDMA
UMTS : Universal Mobile Telephone Standard
HSPA : High Speed Packet Access
HSDPA : High Speed Downlink Packet access
LTE : Long Term Evolution
WiMAX : Worldwide Interoperability of Microwave Access
GSM : Global System of Mobile communication
DAMPS : Digital Advanced mobile Phone System
PDS : Personal Digital Cellular
IS-95 : Interim Standard 95
GSA: Global Mobile Suppliers Association
MIMO : Multiple Input Multiple Output
LTE as 3G
3GPP as the platform of legacy 3G vendors understood the technological limitation of CDMA/WCDMA over OFDMA soon. So, they declared ahead of time their new standard LTE (also UMB by 3GPP2 initially) with OFDMA technology to show a reassuring roadmap to the existing mobile operators.

LTE is scalable to allow operation in a wide range of spectrum bandwidths, from 1.4 – 20 MHz, using
both FDD and TDD modes, thus providing flexibility to suit any operator’s existing or future frequency allocation. LTE and HSPA are complementary to ensure seamless inter-operability. On December 11, 2008 3GPP confirmed approval of the functional freeze of LTE as part of Release 8.

LTE is declared as the natural migration choice for GSM/HSPA operators. LTE is also the next generation mobile broadband system of choice more to leading CDMA operators, who are expected to be in the forefront of service introduction.

At this moment 26 network operators have committed to deploy 3GPP LTE systems and 10 LTE networks are expected to launch commercial services in 2010.
Probably LTE is also a major affair really caused 3G to go slow.

What is 4G?

Whenever there is a great breakthrough over the present technology constraint, the next generation is acknowledged. Mobile WiMAX as a commitment of extra high data rate (75 MBPS) declares it as 4G mobile broadband technology. The 3G legacy vendors though don’t agree on WiMAX as 4G. They have themselves declared OFDMA based LTE as 3G & beyond with a commitment of 200/100 Mbps data rate. Nevertheless, many people call LTE as 4G. Declared features of 4G are as follows-
> MIMO & MU-MIMO technology
> Software Defined Radio, SDR (Use of different air interface, download new modulation/coding)
> Dynamic spectrum allocation (Spectrum on demand)
> Packet network with all IP system
> Voice & data any time anywhere
> Multimedia messaging, Mobile TV, HDTV

In normal practice vendors feel proud to declare a new generation of their product. Here LTE with OFDMA, being a great breakthrough over the WCDMA is not declared as 4G. The reason that makes sense is that, as they are still marketing 3G, declaration of 4G will contradict marketing 3G. Therefore they are calling it as 3G & beyond.

3G World Deployment Scenario

> GSA regularly surveys the evolution of mobile to 3G and beyond, and confirms:
> 275 commercial WCDMA operators in 116 countries at this moment.
> WCDMA is the leading 3G system globally with 72% commercial networks share
> Over 94.1% of commercial WCDMA operators have launched HSPA service
> 287 million WCDMA subscribers (Q4 08)
> 102.3 million WCDMA subscriptions added in 2008; 55.4% growth
> 286 HSDPA operator commitments in 121 countries
> 259 HSDPA operators commercially launched in 111 countries
> Over 71% of commercial HSDPA operators support 3.6 Mbps peak or higher
> Over 37% of commercial HSDPA operators support 7.2 Mbps peak or higher
> Two HSPA+ networks (21 Mbps peak downlink) now in commercial service
> 84 operators committed to HSUPA; 71 HSUPA operators launched in 42 countries
> 1,409 HSDPA devices launched by 169 suppliers; 242 HSUPA devices launched
> 271 HSPA devices incorporate GPS/navigation capabilities
> Over 1.83 billion GSM & WCDMA-HSDPA subscribers in HSPA-enabled networks

Bangladesh Market Scenario

Present Market

The mobile market scenario of Bangladesh is different in many aspects with outside world. The key points are as follows-

> High growth but low ARPU (probably the lowest in the world).
> Licensing 6 mobile and 12 PSTN operators question about regulator’s vision.
> Huge unnecessary investment has been made in absence of policy of resource sharing.
> Absence of policy against SMP (Significant Market Power).
> WiMAX licensing questions 3G licensing at present stage.
> PSTN operators are in the question of survival.

The key potential of the market is the high population density. Probably this factor has dared the operators to be aloof of resource sharing.

About 3G licenses

Asia Pacific countries like India, Pakistan, Thiland etc are in the cutting age to license 3G by 2009. Vietnam already issued license in last month. Bangladesh as part of the region is planning to award 3G license soon. Vendors are competitive to present their 3G product describing colorful services to the operators. They are also in touch with the regulator including the govt. policy makers to take immediate step toward 3G.

3G business risk

> Initial license fee & annual fee will burden the small operator.
> Challenge to meet up coverage & service target.
> Sufficient spectrum allocation (minimum 2 carrier) is necessary.
> Technology neutrality is essential for 3G license.
> WiMAX may lower the broadband tariff.
> Affordability of costly terminal & low PC penetration.
> Spectrum may be exhausted for flat data rate.
> Integration capability with 2G infrastructure.
> Interference with other band.
> Major renovation to introduce multi-standard.

Vendors’ logic about 3G Licensing

Vendors are egger to see licensing 3G/HSPA in Bangladesh. The downlink packet access of HSPA as declared is 14.4 Mbps and 3.1 Mbps in uplink. They assure the cost of 3G equipment very close to 2G/2.5G. They propose composite network architecture of the radio network with GSM/GPRS & UMTS/HSPA.

During 3G presentation they are also demonstrating the approaching LTE and committing about smooth migration by software up gradation only.

Migration challenge for us

Migration to new technology in Bangladesh is big challenge at this moment. Where most operators are striving to survive after the present investment, new investment with new technology will burden them like anything.
Technology know-how is a challenge for the operator to bargain with the vendor for cost effectiveness. There frequently happens uneven contract between vendor & operator due to technological knowledge gap. In most cases vendors are in advantage.

Purchasing proprietary equipment is another challenge to the operator. For proper optimization of the composite 2G/3G network, operator’s better choice is the proprietary vendor that becomes the ultimate inconvenience to the operator.
Though only the software up gradation is the commitment of 3G product series from UMTS to LTE, it will not be possible if new frequency band is allocated for LTE.
Software up gradation sometimes becomes unmanageable on bargain. When the operator will enter in 3G chain, software up gradation to higher protocol will burden the operator.

Should we license 3G?

Before awarding 3G license the regulator as well as the govt. has to go back and calculate the economy of the growth in mobile market. The exponential growth of mobile market during last 3/4 years has given a mobile handset to the rickshaw puller, labor and the school students as well. We have to calculate, if the rickshaw puller and labor would call from a PCO center. What growth in the GDP have we seen against such expenditure on foreign currency for mobile network elements and mobile handsets? If the growth was half, what would have lost?

Further, the regulator should think, would the operator who will be awarded the 3G license may get back the investment surely & survive in the market. If the 3G is awarded, all mobile operators will try hard to get the license. But Regulator should consider the innocence of the operator about the future & this will be the real success of the nation, not by earning revenue from the operator.

If it is decided to award 3G license really now, will the operator to pay additional licensing cost? How many Operators are to award 3G license? If only few operators are awarded, other may loose market share. If all are licensed, may we manage the frequency band as per requirement of the technology? If WCDMA license is awarded will it restrict OFDMA?

On the other hand, if we wait for the 2/3 years (with GPRS/EDGE) till the PC penetration reach to a optimum level (to use broadband effectively) and use WiMAX for broadband internet at this moment, what would we lose? Considering all the threats should we wait for LTE and save a huge additional investment on 3G?


I personally have no answer of my question. Of course I have my personal thoughts, but it does not matter. It is a matter of thought of the nation as whole. On every body’s participation, the ultimate decision must go in favor of us as committed by Almighty.

Writer: Mr. Habibur Rahman, GM, Marketing, Teletalk Bangladesh Ltd

Related Article :

Wednesday, June 3, 2009

Curbing Illegal VOIP: Is DPI a Panacea?

A. K. M. Habibur Rahman

1. Introduction

Voice over Internet Protocol (VOIP) is a much-talked issue in the Information Communication Technology (ICT) sector especially in Bangladesh. It is generally believed that overseas call termination using VOIP started during 2000 when the use of VSAT was liberalized with the aim at promoting software export. Until Bangladesh Telecommunications Regulatory Commission (BTRC) formed in 2002, the regulatory functions of telecommunications sector had been overseen by the Ministry of Post and Telecommunications (MOPT). Under the guidance of MOPT, the then government operator BTTB led actions against illegal voice termination using VOIP.

After BTRC came into being, it has been hunting for the effective solution to curb overseas call termination using VOIP technology through employing foreign consultants, conducting workshops and dialogues with the stakeholders. But no consensus was made about legalizing overseas voice communication using VoIP which could be acceptable to all quarters. Through an initiative to open up VOIP in 2007, International Long Distance Telecommunications Service (ILDTS) Policy 2007 came in the telecommunications sector with a layered concept. A three-layer structure for voice communications namely International Gateway (IGW), Interconnection Exchange (ICX) and Access Network Service (ANS) operator and two-layer for data communications namely International Internet Gateway (IIG) and Internet Service Provider (ISP) operator are the outcomes of the ILDTS policy 2007. Three (in addition to BTTB, now BTCL) operators have been granted IGW licenses in the private sector and they are only allowed to exchange overseas voice using IP technology. One IIG has been allowed in the private sector, in addition to BTTB (BTCL) IIG and the IIGs have been instructed to take necessary measures to stop commercial voice communications through IIG gateways.

It was supposed that call termination using VOIP technology would be minimized once the IGWs in private sector have been established. But what has been experienced since the IGWs started operation? Despite measures taken by IIGs vis-à-vis vigilances conducted by BTRC’s VOIP Prevention Team and legal actions taken by BTRC, it is hard to say that the illegal activities of call terminations in grey routes have come under full control. Consequently, pressures mounted over IIGs to control voice termination through internet and an idea spread over all concerned that VOIP can be automatically stopped by installing Deep Packet Inspection (DPI) device in the IIGs. How far it is right?

2. Fighting Against Illegal VOIP: Technical Approach

There are various ways those were applied in the Internet Gateway to hinder voice communications. The ways worked temporarily but could not automatically stop voice transmission because illegal VOIP operators applied new techniques very quickly. The ways and means against VOIP are described below.

2.1 Port blocking
In computer networking, the protocols of the Transport Layer of the Internet Protocol Suite, most notably the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP), but also other protocols, use a numerical identifier for the data structures of the endpoints for host-to-host communications. Such an endpoint is known as a port and the identifier is the port number (Wikipedia). The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses.

There are some standard ports which have been registered for protocols related to voice communication over IP network e.g. port number 5060 for SIP, 5005 for Real-time Transport Protocol control protocol, 1720 for h323hostcall, 1300 for H323 Host Call Secure etc. At one point of time, it was advised by different experts and by news media that VoIP can be stopped by blocking the ports related to voice communications. So, port blocking was the earliest measure applied in the Internet gateway since there were no facilities to capture, store, and analyze the gateway data traffic. Afterwards, it was clear to everybody that port block is not the way to fight against illegal VoIP. Voice packets can be passed through any port like 80 (used for Hyper Text Transfer Protocol i.e. for browsing) or even 25 (Simple Mail Transfer Protocol i.e. used for mail sending). Should these ports be blocked? The answer must be ‘NO’.

When standard ports were blocked, the VoIP operators refrained from using standard ports for voice protocols. They were to search for new techniques and the technological development always in favour of them finding the new way.

2.2 Traffic Monitoring
After all the private-sector IGWs and IIG came into operation, it was observed that the term DPI has become a buzzword to all concerned. Everybody was telling that DPI implementation is very crucial and without DPI implementation VOIP cannot be stopped. An idea was deep-seated among those concerned that DPI could automatically and effectively stop VOIP.

Deep Packet Inspection (DPI) is an advanced method of packet filtering that functions at the Application layer of the OSI (Open Systems Interconnection) reference model. The use of DPI makes it possible to find, identify, classify, reroute or block packets with specific data or code payloads that conventional packet filtering, which examines only packet headers, cannot detect. (Source:

DPI is generally used for the following purposes:
To detect the Distributed Denial of Service (DDoS) packets and filter them out.
To tighten network security by preventing viruses and spyware from either gaining entrance to a network or leaving it.
To apply network-access rules easily.
To make the network Lawful Interception (LI) compliant.
To enforce service-level agreements by ISPs.
To ensure quality of service by instigating traffic control and bandwidth allocation.
To detect illegal content

The operators use DPI for such applications which have the potential to give users a better internet experience.

DPI uses signature-matching technology i.e. it takes the incoming packets apart, examines the data, comparing with set criteria, and then re-assembles the packet. Based on pre-defined criteria, DPI makes a decision on whether or not to let the packet pass through.

When implemented, some positive performance has been observed but that lasted for a short time. Although DPI has been designed for exploiting various network benefits but it is being used only targeting voice communication. While the performance of DPI was evaluated, it was observed that the DPI can automatically stop those voice packets which uses standard voice protocols and matches the pre-defined rules implemented in the DPI. DPI cannot detect the voice traffic passing through it but using Virtual Private Network (VPN) technology. Most of the illegal voice traffics are passed through VPN tunnel using IPSec, GRE (Generic Route Encapsulation) or open-VPN protocols. These cannot be detected by DPI or cannot be decrypted without specific decrypting software. In this context, DPI can only be considered as the ‘first line of defense’ for fighting against illegal overseas voice transmission.

3.0 What’s Next?

Against DPI’s inability to detect voice packets passed through VPN tunneling, further inspection/analysis of data packets became necessary. There are various softwares which can capture, inspect and analyze the data packet and more detail information can be gathered from the analysis. Two of such application softwares are briefly described below.

Wireshark: This is free software that can intercept and log traffic passing over a data network. When data streams pass through the network, the software captures each packet, decodes & analyzes its content and presents lots of information. It can "understand" the structure of different networking protocols. Thus, it is able to display the encapsulation and the fields along with their meanings of different packets specified by different networking protocols. The important features of Wireshark are:

It can capture from a live network.
It can read from different types of network, including Ethernet, IEEE 802.11 etc,
It can display the captured data in tabular as well as different graphical modes.
It can display filtered data as per need.
It can create Plugins for dissecting new protocols

NetFlow: This is a network protocol analyzer developed by Cisco Systems to run on Cisco IOS-enabled equipment for collecting and analyzing IP traffic information. This is Cisco-proprietary application software but supported by platforms other than Cisco, such as Juniper. Netflow feature enabled Cisco routers generate netflow records in User Datagram Protocol (UDP) or Stream Control Transmission Protocol (SCTP) packets.

Others: Other vendors provide similar features for their routers but with different names- such as Jflow or cflowd for Juniper Networks, NetStream for Huawei Technology, Cflowd for Alcatel-Lucent etc.

Use of the network protocol analyzing software needs a set of resources:
a strong hardware platform for an IIG handling data traffic at the rate of more than 2 Gigabit per second.
a team of experienced and well-trained network engineers to capture, analyze the data and implement the policy. This should be done on continuous basis.

4. Post-analysis Activities

After analyzing the traffic, if suspected packet (voice) is detected what should be done? From the operator perspective, there is only one thing to do: block the source and destination IP addresses and report the addresses to the regulator. From the regulator perspective, the regulator can investigate the issue even by physically sending authorized personnel and take legal measures for breaching the terms and conditions of the license for designated service.

In this scenario, packet filtering has been becoming a complex task as call centers are allowed to do VoIP originating from and terminating to a specific IP address and video conferencing involves real time voice transmission.

It was observed that blocking IP addresses is also not the effective technical way because as soon as one or some IP addresses are blocked illegal voice operators can switch over to different IP addresses. They might have handsome numbers of IP addresses in their hand.

There are some other measures which might be helpful to some extent for curbing illegal voice communication over Internet but this could have adverse impact on the legitimate data traffic. The measures include: limiting excessive (also doubtful) packets (like DNS), protocol (UDP), application (GRE, IPSec, PPP encapsulated) traffic to some reasonable level, providing asymmetric bandwidth to the ISPs, etc

Commercial voice is termed as illegal voice whereas non-commercial voice is not illegal. As per regulatory guidelines, magnitude of non-commercial voice must be limited to a certain level and that level shall be determined by the regulator. As both commercial and non-commercial voice transmission over Internet use same technology, it is very difficult to distinguish between both from technical point of view. Limiting the non-commercial traffic means applying different policy implemented in the Gateway which may cause stopping or degrading the legal traffic.

5. Conclusion

In fact, there is no single solution which can AUTOMATICALLY stop all voice packets passing through an IP network. Continuous monitoring of traffic (almost 18 hours in a day) and applying policy in the network based on observations received from analysis, regular vigilances by the regulator may keep the magnitude of illegal voice communication at a minimum level. This will surely need a dedicated team having experienced and well-trained personnel equipped with effective software and high-end hardware platform at the operators’ end and assistance of law enforcing agencies as well as deployment of in-house expert personnel at the regulator end. .