Amity Institute Of Telecom Technology And ManagementAN INTERNSHIP EXPERIENCE REPORT BY SnILVANGI SnAkMA A16071080S3 8Ŧ1LCnŦ (LLLC1kCNICS Ǝ 1LLLCCMMUNICA1ICN) 8A1Cn 2008Ŵ12 INTERNSHIP WITH ADVANCL LLVLL 1LLLCCM 1kAINING CLN1kL(AL11C) UNDER THE GUIDANCE OF ShŦ Cm Þa| S|nghţSDL(LWSD]SS1Þ) DURING MAY - 1ULY 2011 CREDIT UNITS: 6 CREDITS TABLE OF CONTENTS 1.1 INTRODUCTION 2.1 ANALYSIS OF THE COMPANY 3.1 INTRODUCTION OF EWSD 3.2 ARCHITECTURE 3.3 CALL SET UP IN EWSD 4.1 SUBSCRIBER ADMINISTRATION 4.2 DIRECTORY NUMBER ADMINISTRATION 4.3 ANALOG SUBSCRIBER ADMINISTRATION 5.1 CONCLUSION 6.1 REFERENCES 1.1)INTRODUCTION A graduate Irom a proIessional institution is expected to be expert in the respective Iield oI specialization. To be proIessionally conIident and globally competitive the student must acquire knowledge, both academically and practically. The knowledge that a student receives in the class room is by and large theoretical, although increased emphasis is given on the practical training also. But the real Iiled experience can be gained iI the academically sound student is exposed to hands-on training in an industry under the guidance oI successIul proIessionals. It not only gives proIessional conIidence to the students but also inculcates in them proIessional ethics. And that is the aim oI internship training. With the aim oI acquiring hands-on training in telecommunication sector, a Iast growing industry globally, I joined the Advanced Level Telecom Training Centre (ALTTC), Ghaziabad. I had thorough basic knowledge in the Iield oI Electronics and Telecommunication, gained Irom knowledgeable, expert and dedicated teaching Iaculty in the Department oI Electronics and Telecommunication, AMITY, Noida (UP). I was particularly interested to learn more about EWSD, Fibre optical communication, Digital Switching & IN Services, GSM, CDMA, Broad Band. I was inspired to join ALTTC Ior internship training because primarily oI two reasons: one, it is a nationally renowned institution, and two, three oI my teachers are trained in this institution and they are really exemplary in knowledge and teaching skills. AIter having joined ALTTC and working in the excellent and well equipped labs I Iound that I had made a right choice Ior my hands-on training in the Iield oI communication. At ALTTC the training modules are tailored beIitting proIessional requirements. Hands-on training on systems is encouraged. The inIrastructure, the labs, the Iaculty and their level oI dedication, and other Iacilities provide a completely proIessional environment, simulating conditions existing in the work environment. During a period oI about 6 weeks, we underwent training on diIIerent aspects oI communication, viz GSM, Broad Band, CDMA, EWSD.I was particularly interested getting training in Electronische Wheler Systeme Digitale (EWSD) because it is the technology regarding how we make a call in landline phones. So it really Iascinated me to study EWSD as me make so many calls everyday and to know how it works was really interesting also it is the upcoming technology in landline phones. We were imparted practical training along with some theoretical aspects relevant to what we actually did during practical. It is said that engineers make the world. Time spent in ALTTC has given me the conIidence to make world as better, eIIicient and beautiIul place to live in.The training which I received Irom ALTTC has not only given me conIidence but will also go a long way in shaping my Iuture career. 2.1)Analysis of The Company Telecommunications sector is growing at a Iast rate. The dependence oI people on the telecommunications has also increased very much. The rapid growth in Indian telecom industry has been contributing to India`s GDP at large. For building reliable telecommunication systems a lot oI engineering and designing is required. An optimized system can only be designed aIter proper planning and consideration oI each and every Iactor that can aIIect working oI the system.BSNL is doing a great job in this regard. Bharat Sanchar Nigam Limited (abbreviated BSNL; ) Iormed in October, 2000, is World's 7th largest Telecommunications Company providing comprehensive range oI telecom services in India: Wireline, CDMA mobile, GSM Mobile, Internet, Broadband, Carrier service, MPLS-VPN, VSAT, VoIP services, IN Services etc. Presently it is one oI the largest & leading public sector unit in India. BSNL has installed Quality Telecom Network in the country and now Iocusing on improving it, expanding the network, introducing new telecom services with ICT applications in villages and wining customer's conIidence.It has about 46 million line basic telephone capacity, 8 million WLL capacity, 52 Million GSM Capacity, more than 38302 fixed exchanges, 46565 BTS, 3895 Node B 3G BTS), 287 Satellite Stations, 614755 Rkm of OFC Cable, 50430 Rkm of Microwave Network connecting 602 Districts, 7330 cities/towns and 5.6 Lakhs villages. BSNL is the only service provider, making Iocused eIIorts and planned initiatives to bridge the Rural-Urban Digital Divide ICT sector. In Iact there is no telecom operator in the country to beat its reach with its wide network giving services in every nook & corner oI country and operates across India except Delhi & Mumbai. Whether it is inaccessible areas oI Siachen glacier & North-eastern region oI the country. BSNL serves its customers with its wide bouquet oI telecom services. BSNL is numero uno operator oI India in all services in its license area. The company oIIers vide ranging & most transparent tariII schemes designed to suite every customer. BSNL cellular service, CellOne, has 55,140,282 2G cellular customers and 88,493 3G customers as on 30.11.2009. In basic services, BSNL is miles ahead oI its rivals, with 35.1 million Basic Phone subscribers i.e. 85 per cent share oI the subscriber base and 92 percent share in revenue terms. BSNL has more than 2.5 million WLL subscribers and 2.5 million Internet Customers who access Internet through various modes viz. Dial-up, Leased Line, DIAS, Account Less Internet(CLI). BSNL has been adjudged as the NUMBER ONE ISP in the country. BSNL has set up a world class multi-gigabit, multi-protocol convergent IP inIrastructure that provides convergent services like voice, data and video through the same Backbone and Broadband Access Network. At present there are 0.6 million DataOne broadband customers. The company has vast experience in Planning, Installation, network integration and Maintenance oI Switching & Transmission Networks and also has a world class ISO 9000 certiIied Telecom TrainingInstitute. Scaling new heights oI success, the present turnover of BSNL is more than Rs.351,820 million US $ 8 billion) with net profit to the tune of Rs.99,390 million US $ 2.26 billion) for last financial year. The inIrastructure asset on telephone alone is worth about Rs.630,000 million (US $ 14.37 billion). 2007 has been declared as "Year oI Broadband" in India and BSNL is in the process oI providing 5 million Broadband connectivity by the end oI 2007. BSNL has upgraded existing Dataone (Broadband) connections Ior a speed oI up to 2 Mbit/s without any extra cost. This 2 Mbit/s broadband service is being provided by BSNL at a cost oI just US$ 11.7 per month (as oI 21 July 2008 and at a limit oI 2.5GB monthly limit with 0200-0800 hrs as no charge period). Further, BSNL is rolling out new broadband services such as tripleplay. BSNL is planning to increase its customer base to 108 million customers by 2010. With the Irantic activity in the communication sector in India, the target appears achievable. BSNL is a pioneer oI rural telephony in India. BSNL has recently bagged 80° oI US$ 580 m (INR 2,500 crores) Rural Telephony project oI Government oI India. On the 20th oI March, 2009, BSNL advertised the launch oI BlackBerry services across its Telecom circles in India. The corporation has also launched 3G services in select cities across the country. Presently, BSNL and MTNL are the only players to provide 3G services, as the Government oI India has completed auction oI 3G services Ior private players. BSNL shall get 3G bandwidth at lowest bidder prices oI Rs 18,500 crore, which includes Rs 10,186 crore Ior 3G and Rs 8313crore Ior BWA. BSNL management has paid this money under protest seeking reIund. BSNL also launched an Entertainment Portal called BSNL Hungama which provides contents like music and music video to users Ior download. This Iunctions as a Iixed monthly plan. The turnover, nationwide coverage, reach, comprehensive range oI telecom services and the desire to excel has made BSNL the No. 1 Telecom Company oI India. BSNL SERVICES O BSNL LANDLINE O FIXED LINE PRE-PAID O BSNL PCO O PHONE PLUS SERVICE O NEW TELEPHONE CONNECTION O PERMANENT CONNECTION O CONCESSION IN RENTALS O SHIFT OF TELEPHONE O SAFE CUSTODY OF TELEPHONES O TRANSFER OF TELEPHONE O TELEPHONE TARIFF O HELP DESK O BSNL MOBILE O 3G SERVICES O BSNL WLL O INTERNET SERVICES O BSNL BROADBAND O BSNL MANAGED NETWORK SERVICES O GLOBAL CONFERENCING O BSNL MPLS-VPN O ISDN O LEASED LINE O INTELLIGENT NETWORK O VIDEO CONFERENCING O AUDIO CONFERENCING O ENTERPRISE SOLUTION O TELEX/TELEGRAPH O EPABX O DATA COMMUNICATION BSNL also has many training institutes. Most popular among them are: (1) Advance Level Telecom Training Centre (ALTTC),Ghaziabad (2) Bharat Ratna Bhimrao Ambedkar Institute oI Telecom Training (BRBRAITT),Jabalpur (3) Regional Telecom Training Centre (RTTC),Hyderabad I planned to do my summer internship at ALTTC. ALTTC Advanced Level Telecom Training Centre (ALTTC), Ghaziabad is the apex training institute oI BSNL. An ISO 9001: 2008 accredited institute, ALTTC was set up as a joint venture oI International Telecommunication Union, Geneva, UNDP and the Government oI India in 1975. ALTTC Iunctions on the Irontiers oI telecom technology, Iinance and management and imparts training to the leaders in the business. The strength oI ALTTC lies in the state oI art labs, massive inIrastructure and trained, talented and qualiIied human resource pool. The Centre's Mission statement is To Deliver Excellence Through Training . The training areas cover vast spectrum oI topics such as Digital Switching and IN, Mobile Communication: GSM, 3G CDMA Data communication: Broadband and Networking, Optical Networks: SDH, DWDM, NGN, Access Networks, Management, Telecom Finance, InIormation Technology, Building Science (Civil and Electrical) and Telecom Network Planning. Advanced Level Telecommunication Training Center, Ghaziabad - India, located about 30 Km. Irom New Delhi, is a selI-contained campus Iull oI liIe and amenities. It is spread over a lush green landscape oI over 80 acres oI land. Besides main building complex which houses the administrative oIIices, class rooms and laboratories, there are elaborate Iacilities like hostel Ior trainees, residential complex, shopping center, bank, Wi-Fi Connectivity is available and Participants bringing their Laptops with them, will be provided with USB Adaptors at the Hostel and post oIIice etc. ALTTC has excellent Iacilities Ior training. The lecture rooms at the ALTTC are equipped with modern teaching aids. Emphasis is given on simulation oI conditions existing in the work environment. Hands-on training on systems is encouraged. CBT packages are available Ior selI paced learning. ALTTC has well equipped laboratories /model exchanges Ior Training in switching systems. The Iacilities include switching systems laboratories equipped with C-DoT, Ericsson's AXE-10, Fujitsu's FETEX-150, Siemens's EWSD and Alcatel's E-10B systems. ALTTC is equipped with well organized library containing books on telecommunication, computer, management and others. Also having internet Iacility. ALTTC is equipped with a variety oI In-door and Out-door sports activities- Lawn Tennis O Table Tennis O Billiards O Badminton (In-door court) O Basket-Ball O TV Room, Books etc. There are three well Iurnished hostels providing residential Iacilities to around 400 participants. Wi-Fi Iacility is also provided to the students. INTERNSHIP EXPERIENCE 3.1) INTRODUCTION OF EWSD The Department oI Telecommunications had announced ambitious plans Ior the addition oI 7.5 million lines to the existing 5.8 million by the end oI the 8th plan (1992-97) as compared to only 3.2 million in 1982-92. Consequent upon delicensing oI the Telecom. equipment and throwing it open to Ioreign investments, six new technologies were planned to be validated. These Ioreign suppliers set up their validation exchanges, each oI 10,000 lines capacity (including two RSUs oI 2K each), at diIIerent places, e.g. EWSD oI Siemens (Germany) at Calcutta, AXE-10 oI Ericsson (Sweden) at Madras, Fetex-150 oI Fujitsu (Japan) at Bombay, OCB-283 oI Alcatel (France) at Delhi etc. EWSD is one oI the technologies selected Ior TAX and is also the technology Ior Intelligent Network and Mobile Communication. This article gives a general introduction to the EWSD system, its Ieatures, architecture and Iacilities. EWSD Digital switching system has been designed and manuIactured by M/s Siemens, Germany. The name is the abbreviated Iorm oI German equivalent oI Electronic Switching System Digital (Electronische Wheler Systeme Digitale). ESWD entered the world market in 1981, it was one oI the Iirst Iully digital switching systems. By 1994 some 85 million ports in EWSD technology had been put into service by about 200 operating companies in 85 countries. This international market success is based on the extraordinary reliability and high economic eIIiciency oI ESWD, its continually advancing state oI the art technology and ever growing number oI Ieatures Ior subscribers and operating. EWSD switch can support maximum 2,50,000 subscribers or 60,000 incoming, outgoing or both way trunks, when working as a pure tandem exchange. With its universality and Ilexibility, EWSD can be used economically in diIIerent network structures as a network node oI variable size Ior switching the most varied types oI inIormation and can be adapted Ilexibly to changing requirements.The dynamic capacity oI the system can handle a traIIic load oI up to 25.600 erlangs with 2.5 million BHCA(Busy hour call attempts). So EWSD oIIers adequate reserves oI capacity oI any application that may arise in practice.The EWSD is a highly successIul digital electronic switch system. It is a powerIul and Ilexible Ior public communication networks and over 250 million EWSD switching nodes have been deployed since its introduction in the telecommunications Iield.The EWSD switching system employs a Iully digital design concept. It provides a wide and expandable range oI Ieatures and services, an extensive saIeguarding concept and a high data transmission quality. The EWSD switching system is designed with a modular approach in every component used in the system. The EWSD is divided into three parts-soItware,hardware, and physical structure. The soItware, hardware and physical units oI the EWSD are modular in design. Modules M:X): Smallest units in the system. The type oI module depends on the hardware subsystem in which they are used. Fig1)-Physical Structure FramesF:X): Group oI modules oI certain hardware subsystem Iorm a Irame. Racks R:X): Frames together Iorm a rack. Rack Row: Line oI racks Iorm a rack row. Fig(1) clearly shows that the physical structure uses a modular concept. The node is divided into Iour sections. The hardware architecture is designed in such a way that every subsystem oI it has same design i.e. modules, Irames, racks. ADVANTAGES 1) It provides eIIective saIeguarding. 2) It gets Ilexibly adapted to the network environment. 3) It provides cost eIIicient adaptation to the Iuture changes. 4) There is a simpliIication oI installation and maintenance. 5) It provides a variable range oI Ieatures. 3.2) SYSTEM ARCHITECTURE The hardware oI the EWSD is designed to have Ilexibility oI expansion in the system to the Iuture requirements without halting the operation oI the switch and to have the simplicity oI installation.For these reasons modular concept is used in hardware architecture.The EWSD switch is divided into Iour major subsystems which are Iurther divided into subparts.The Iour major subsystems are: 1) Access 2) Switching Network 3) Signaling network 4) Coordination complex The main hardware units oI an EWSD switch are as under:- (1) Digital line unit (DLU) - Iunctional unit on which subscriber lines are terminated. (2) Line/Trunk Group (LTG) - Digital Trunks and DLUs are connected to LTGs. &C Common channel signaling/ Signaling System Network Control È Access Switcbing Wtwork Fig(2)- The access function determined by the network environment are handled DLUs and L1Gs Ŧ (3) Switching Network (SN) - All the LTGs are connected to the SN which interconnects the line and trunks connected to the exchange in accordance with the call requirement oI the subscribers. CCNC and CP are also connected to SN. (4) Coordination Processor (CP) - It is used Ior system-wide coordination Iunctions, such as, routing, zoning, etc. However each subsystem in EWSD carryout practically all the tasks arising in their area independently. (5) Common Channel Signaling Network Control (CCNC) Unit or Signaling System Network Control (SSNC)- This unit Iunctions as the Message TransIer Part (MTP) oI CCS#7. The User Part (UP) is incorporated in the respective LTGs. Block diagram oI EWSD is given on previous page. It also shows that the most important controls are distributed throughout the system. This distributed control reduces the coordination overheads and the necessity oI communication between the processors. It results in high dynamic perIormance standard. For inter-processor communications , 64 kbps semipermanent connections are set through SN. This avoids the necessity Ior a separate interprocessor network. 3.2.1) DIGITAL LINE UNIT DLU) DLU is used to connect the subscribers to the switch and to concentrate the subscribers` traIIic in the direction oI the EWSD network node. These can be installed as part oI the network node in an exchange (local) or as remote connection units in the vicinity oI a subscriber group called as remote DLU. Remote DLUs can be installed in permanent buildings, in containers or in shelters (Ior small groups oI subscribers).The short subscriber lines obtained in this manner and the concentration oI subscriber traIIic to the network node on digital and Iiber-optic transmission links result in an economical subscriber network with optimum transmission quality. The DLU is an intermediate stage Ior the connection oI the external environment to the exchange. The lines that are connected to it are subscriber lines, ISDN lines and digital subscriber lines. On the other side oI the DLU, towards the EWSD side, it has PDC links going towards the LTG. These lines are also called external interIaces to the DLU. Besides these there are internal interIaces present in it also which are used to connect its internal components. These interIaces include the voice and data speech highway with a data rate oI 4096 Kbps and a control network with a data rate oI 136Kbps. These two networks are duplicated Ior saIeguarding purposes.The DLU and LTG are connected to each other in three diIIerent modes via 2, 3, or 4 PDC links namely: (1) Direct (2) Crossover (3) Random One DLU is connected to two diIIerent LTGs Ior the reasons oI security. A local DLU is connected to two LTGs via two 4 Mbps (64 TSs) links, each towards a diIIerent LTG. In case oI remote DLUs, maximum 4 PDCs oI 2 Mbps (32 TSs) are used per DLU, two towards each LTG. Hence total 124 channels are available between a DLU and the two LTGs, out oI which 120 channels are used Ior user inIormation (speech or data) and signaling inIormation is carried in TS16 oI PDC0 and PDC2. In case oI a local DLU interIace, TS32 carries the signaling inIorma- tion. Within the DLU, the analog subscribers are terminated on SLMA (Subscriber Line Module Analog) cards (module). Similarly Digital (ISDN) subscribers are terminated on the SLMD modules. Each module can support 16 subscribers, hence has 16 SLCA/SLCDs (Subscribers Line Circuit Analog/Digital) and one processor SLMCP. One DLU can carry traIIic oI 100 Erlangs. A standard rack oI DLU (local ) can accommodate two DLUs oI 952 subscribers each. In case the link between a remote DLU and the main exchange is broken, the subscribers connected to the remote DLU can still dial each other but metering will not be possible in this case. For emergency service DLU-controller (DLUC) always contain up-to-date subscribers data. Stand Alone Service Controller card (SASCE) is provided in each R-DLU Ior switching calls in such cases ( call setup and release Ior analog and ISDN subscribers and enables DTMF dialling Ior push-button subscribers). This card is also used Ior interconnecting a number oI remotely situated DLUs (maximum 6), in a cluster, called a Remote Control Unit (RCU), so that subscribers connected to these remote DLUs can also talk to each other in case the link oI more than one DLU to the main exchange is broken. CS PDC2 with CCS PDC1 without CCS PDC0 with CCS Subscriber lines and PBX lines for small and med- ium-sized PBXs Remote application Local application 4Mbps SN LTG LTG 4 Mbps DLU DLU Subscriber lines and PBX lines for small and medium-sized 3.2.1.1) DLUG The latest version oI the DLU which is used in the EWSD switches these days is DLUG. It is the most powerIul subscriber line concentrator unit. The enhancements oI the DLUG are in the terms oI increased number oI subscribers that can be connected to a single module. The increase is both in the digital as well as analog subscribers.Using a single module oI SLMA & SLMD up to 32 analog subscribers and 16 digital subscribers respectively can be connected. This is because oI the increase in the number oI the SLCA and SLCD in the module. In addition to this there is 50° reduction in the space requirements in the per analog subscriber line. The power consumption is also lowered by 30° to 1050W at maximum load. It can be connected to Iour LTGs with 16 PDCs with a provision oI one signalling channel (CCS) per LTG. It can handle up to 390 Erlangs oI traIIicŦ 3.2.2) LINE TRUNK GROUP LTG) The Line/Trunk Groups are the interIaces between the Switching Network and the network environment oI the exchange which maybe analog or digital. It may be connected to trunks as well as a DLU. The LTG is connected to both the planes oI the switching network to improve saIeguarding. II the link between the LTG and one oI the switching network Iails, call processing will continue unrestrictedly. The line/trunk groups (LTG) Iorms the interIace between the digital environment oI an EWSD exchange and the switching network (SN).Maximum traIIic handling capacity per LTG is 100 Erlang. The LTGs are connected in any oI the Iollowing ways : (i) Via 2/4 Mb/s PDCs with remote/local DLUs to which subscribers are connected (ii) Via 2 Mbps digital access lines to other digital exchanges in the network ( MF R2 Trunks, CCS#7 Trunks) (iii) Via Primary rate Access lines to ISDN PBXs (ISDN subscribers with PA) (iv) V5.2 Trunks, Announcements Trunks, OCANEQ, X.25 Links Ior PSPDN, IP (SSP) The LTG has Iollowing Iunctions: 1) It receives and evaluates the inIormation oI trunks and subscriber lines. 2) It also sends signals and tones. It sends and receives messages Irom and to the coordination processor (CP) and the group processor. 3) It adapts the line conditions (transmission Iormat) to the 8Mbits /sec highway oI the SN. 4) It detects LTG Iaults. 5) It detects Iaults on the exchange internal link interIaces during call processing. 6) It reports Iaults and routine messages to the coordination processor. 7) It evaluates the Iaults and initiates processes, such as blocking the LTG. 3.2.2.1) LTGP LTGP is the latest one and is characterized by improved perIormance and a much compact design. In LTGP all the basic Iunctions oI Iour LTGs are combined on the single module. This type has the capacity oI receiving 16 PDC links Irom DLU and other exchanges. 3.2.3) SWITCHING NETWORK DiIIerent peripheral units oI EWSD, i.e., LTGs, CCNC, MB are connected to the Switching Network (SN) via 8192 kbps highways called SDCs (Secondary Digital Carriers), which have 128 channels each. The SN consists oI several duplicated Time Stage Groups (TSG) and Space Stage Groups (SSG) housed in separate racks. Connection paths through the TSGs and SSGs are switched by the Switch Group Controls (SGC) provided in each TSG and SSG, in accordance with the switching inIormation Irom the coordination processor (CP). The SGCs also independently generate the setting data and set the message channels Ior exchange oI data between the distributed controls. The switching network is always duplicated (planes 0 and 1). Each connection is switched simultaneously through both planes, so that a standby connection is always immediately available in the event oI a Iailure. Each TSG can accommodate 63 SDCs Irom LTGs and one SDC to MB. One SDC is extended Irom SGC oI each TSG and SSG towards MB. Thus one TSG can handle upto 63 LTGs. The switching network can be expanded in small stages by adding plug-in modules and cables and iI necessary by assigning extra racks. Optimized switching network conIigurations are available in a range oI sizes. The smallest duplicated SN:63 LTG conIiguration which can handle 30,000 subscriber lines or 7,500 trunks when Iully equipped is installed in a single rack and can handle 3150 erlangs traIIic. In its maximum conIiguration, the EWSD switching network has 8 TSGs and 4 SSGs (in 12 Racks) to connect 504 LTGs and has a traIIic - handling capacity oI 25,200 erlangs. SNs Ior 126 LTGs and 252 LTGs are also available which can handle 6300 and 12600 erlangs traIIic respectively. SN(B) has only 5 types oI modules and each TSG and SSG is accommodated in only two shelves oI the respective racks. Remaining Iour shelves accommodate LTGs. MAIN FUNCTIONS: O Speech Path Switching O Message Path Switching O CCS#7 signaling channels connection (NUC) 3.2.3.1) SWITCHING The primary Iunction oI a switching system is to establish a connection between two points. The major component oI the switching system or exchange is the switching matrix. Apart Irom the switching matrix, the switching system consists oI many other Iunctions to perIorm call processing. 3.2.3.2) SWITCHING-BASIC CONCEPT Switching matrix is the hardware that provides the connectivity between any input - output line pair. There may be n inlets and m outlets and these inlets/outlets may be connected to subscriber lines or trunk lines (see Iigure 3). Fig(3)-Switching Matrix When all the input lines and output lines are connected to subscribers then the switch provides the connectivity among the subscribers connected. In this case, there can be n/2 simultaneous conversations that can be connected by the switching matrix. This type oI a switch is said to be non-blocking, in other words, no subscriber is denied a connection Ior want oI switching resources. Normally, not all the subscribers converse simultaneously. Hence, a switch is designed to cater to the average number oI simultaneous calls that is expected. This design may, occasionally, bring up a situation when there is no Iree switching path available, when a subscriber requests a connection. This is called a blocking switch in which the number oI simultaneous connections possible is less than the maximum number oI simultaneous conversations possible. 3.2.3.3) SWITCHING TECHNIQUES DiIIerent methods are employed to establish the required connection in an exchange. The two most widely used methods are time switching and space switching. Space switching was exclusively used in electromechanical switching systems and with the advent oI digital technology, time switching has become a popular option. Also, to increase the switching capacity combination oI time and space switching methods are also employed. This is called combination switching. 3.2.3.4) COMBINATION SWITCHING There are some limitations in both time and space switching that can be overcome by multistage and combination switching.These structures also permit to increase the switching capacity Ior a given technology. A combination switch can be built by a number oI stages oI time (T) and space (S) switches. A three-stage combination switch in which time stages are placed on either side oI a space stage is reIerred to as TST switch.Other multistage typical conIigurations include TSST, TSSSST and TSTSTSTS. FIG4) 3.2.4) COORDINATION COMPLEX The EWSD system incorporates largely independent subsystems with a separate microprocessor control. The coordination processor handles the coordination oI these microprocessor controls and data transIer between them. The coordination complex has been divided into diIIerent units Ior coordinating diIIerent parts oI the EWSD. These parts will be discussed in the Iollowing sections. 3.2.5) COORDINATION PROCESSOR For making the EWSD a Ilexible and powerIul system the EWSD the diIIerent subsystems oI the EWSD are designed with their own separate controls. The common control unit CP controls all the common system procedures and coordinates the operating, saIeguarding and the switching processes. The coordination processor (CP) handles the data base as well as conIiguration and coordination Iunctions, e.g.: O Storage and administration oI all programs, exchange and subscriber data. O Processing oI received inIormation Ior routing, path selection, zoning, charges O Communication with operation and maintenance centres O Supervision oI all subsystems, receipt oI error messages, analysis oI supervisory result messages, alarm treatment, error messages, alarm treatment, error detection, error location and error neutralization and conIiguration Iunctions. O Handling oI the man-machine interIaceŦ The CP113C is multiprocessor and can be expanded in stages. In the CP113C, two or more identical processors operate in parallel with load sharing. The rated load oI n processors is distributed among n¹1 processors. This means that iI one processor Iails, operation can continue without restriction (redundancy mode with n¹1 processors). The Basic Iunctional units oI CP 113C are as Iollows: O Base Processor (BAP) Ior operation & maintenance and call processing, O Common Memory (CMY)- 64 to 1024 MB in 4 memory banks consisting oI 4 Mb DRAM chips. O Input / Output Controller (IOC) - 2 to 4 IOCs coordinate and supervise accessing oI CMY by IOPs. O ATM Bridge Processor (AMP) II a SSNC (EWSD powernode) is connected, the AMP is used (usually instead oI the second IOC pair). It represents the interIace between the ATM equipment in the SSNC and the CP. Its task is to convert the ATM oriented data streams Irom SSNC to the internal EWSD Iormat. O Input/output processors (IOP) - Various types oI IOPs are used to connect the CP113C to the other subsystems and Iunctional units oI the exchange as well as to the external mass storage devices (EM i.e., MDD, MTD, MOD), the two O&M terminals (OMT/ BCT), to OMC via data lines etc. Maximum 12 IOPs can be connected to one IOC. The Iigure is shown on next page.The other Iunctional units oI CP 113C are call processors (CAPs) which deal only with call processing Iunctions. Hardware wise they are similar to BAPs . 3.2.6) MESSAGE BUFFER MB) It is use Ior coordinating internal message traIIic between the CP, the SN, the LTGs and the CCNC in an exchange. The message buIIer serves as an interIace adapter Ior the internal inIormation exchange between 1) coordination processor 2) Switching network 3) Line trunk group The MB has 1-4 message buIIer groups (MBG) depending on the system size. The MBG are also duplicated. The latest version oI the message buIIer is MB (D) aIter MB (B). The MBB is designed to match the processing capacity oI the coordination processor CP113C. The MBB provides a very high transmission capacity, especially in the message buIIer Ior the line/trunk group (MBU: LTG). 3.2.7) CENTRAL CLOCK GENERATOR CCG) It is use Ior the synchronization oI the exchange and, where necessary, the network. The CCG is extremely accurate (10 -9) . It can,however, be synchronized even more accurately by an external master clock (10 -11 ). For the transIer oI digital inIormation in a network, synchronized Iunctional sequences oI all participating units is an absolute requirement. Accurate clock pulses must be provided Ior all exchanges with in the digital network. This task is handled by the CCG which synchronizes the clock generators in the Iunctional units. II all the clock generators are Iailed nothing would work. It would not be possible to operate the exchange Irom the O&M center, to route speech channels, to record billing data or to display the time at the system panel. Tones would not be generated and above all the evaluation oI the dialed inIormation would not take place. For this reason CCG is duplicated. One CCG operates as the master and the other as slave. The slave is phase locked with the master, thus ensuring a continuous clock supply iI the master Iails. The CCG is synchronized to the external reIerence Irequency. Then the CCG synchronizes all the components oI EWSD to the reIerence Irequency. 3.2.8) SYSTEM PANEL The system panel provides a continuous overview oI the operational status oI a EWSD system.The system panel indicates Iaults visibly and audibly. It also displays the processing load oI the CP, the time and the date. The display area includes 7- segment displays, light emitting diodes and keys. It is organized into display areas Ior LTG, SN, CP & CCNC, external equipment,system internal conditions and the system panel itselI. The displayed processor load is a measure Ior the traIIic load handled by the EWSD system. The system panel also displays alarms like critical alarm, major alarm, minor alarm, minor alarm combined with the major alarm. To turn oII the alarm simply depress the accept key. Upto eight system panels can be connected to the EWSD exchange. It can be remote and may be connected to the system also. The system panel consists oI the Iollowing Iunctional units: SYSTEM PANEL DISPLAY SYPD): It is use to display system internal alarms and the CP load. It thus provides a continuous overview oI the state oI the system. The SYP also displays external alarms such as Iire and air-conditioning system Iailure Ior example. It is installed in the Equipment Room or in the Exploitation Room SYSTEM PANEL CONTROL SYPC): The SYPC handles the input/output control Ior up to 8 SYPDs,24 external supervisory units like smoke detectors, 24 external Iailuers signaling units. 3.2.9) OPERATION AND MAINTENANCE TERMINALS It is use Ior Input/output. Two OMTs/ BCTs are provided Ior O&M Iunctions. 3.2.10) EXTERNAL MEMORY EM) It is use Ior O Programs and data that do not always have to be resident in the CP O An image oI all resident programs and data Ior automatic recovery O Call charge and traIIic measurement data. To ensure that these programs and data are saIeguarded under all circumstances, the EM is duplicated. It consists oI two magnetic disk devices (MDD). The EM also has a magneto optical disk ( MOD) and/or magnetic tape device (MTD), Ior input and output. 3.2.11) COMMON CHANNEL SIGNALING NETWORK CONTROLLER CCNC) A maximum oI 254 common signaling channels can be connected to the CCNC via either digital or analog links. The digital links are extended Irom the LTGs over both planes oI the duplicated switching network and multiplexers to the CCNC. The CCNC is connected to the switching network via two 8 Mbps highways (SDC: CCNC). Between the CCNC and each switching network plane, 254 channels Ior each direction oI transmission are available (254 channel pairs). The channels carry signaling data via both switching network planes to and Irom the LTGs at a speed oI 64 kbps. Analog signaling links are linked to the CCNC via modems. For reasons oI reliability, the CCNC has a duplicated processor (CCNP) which is connected to the CP by means oI similarly duplicated bus system. The CCNC consists oI : O Upto 32 signaling link terminal (SILT) groups, each with 8 signaling links and O One duplicated common channel signaling network processor (CCNP). The Iunctions oI the CCNC depend on its position in a signaling link. In the originating or desti- nation exchange in associated signaling, it operates as signaling end point (SEP) and in transit exchange in quasi-associated signaling, it operates as a signaling transIer point (STP). The CCNC, equipped in one rack can handle upto 48 signaling links. Equipments handling upto 96 signaling links can be equipped in additional racks. 3.2.11.1) SIGNALING SYSTEM NETWORK CONTROL In the EWSD powernode the SSNC takes over the control oI the SS7 network (instead oI CCNC as was used in EWSD Classic). Here SSNC can be used as signaling end point (SEP) or signaling transIer point (STP) as was also done by CCNC. In Contrast to the CCNC, the SSNC is equipped with its own O&M interIace to the Netmanager NetM and with back-up memories (magnetic disk / magneto-optic disk). ThereIore with regard to the OAM, it is independent oI the CP. Thus it is possible to also use the SSNC outside oI EWSD as a stand-alone Signaling TransIer Point STP. 3.3) CALL SETUP IN THE EWSD The call setup in the EWSD switching system involves interaction oI the various hardware subsystems. An overview oI the call setup and the sequence oI various steps are explained in this part.Let us consider subscriber A wants to call the subscriber B. To call subscriber B the CCS via digital data links CCS via analog data links 0 31 0 31 0 7 0 7 SÌLT group 31 SÌLT group 0 CCNP 0 CCNP 1 CP bus system ig{Ź]-ommonbannWSignaingWtworkontro Multiplexer Modem subscriber A initiates a number oI call processing events by liIting the handset. The various steps involved in completion oI the call are: 1) When A liIts the handset the analog subscriber line circuit detects the oII hook condition. 2) The A-SLMCP scans the SLCA and detects request Ior a connection. The A-SLMCP reports this situation to the DLUC. 3) The DLUC then Iorwards the seizure message via digital interIace in the DLU and A-DIU in the A-LTG to the group processor. 4) The GP checks its database Ior the data associated with the A subscriber and assigns time slot on one oI the PCM links and reports this inIormation to the A-SLMCP. 5) A-SLMCP causes the SLCA to loop back the send time slot to the receive slot (test loop). The A-GP through connects to group switch in order to perIorm the speech channel loop test Irom the A-LTG to the A-SLCA in the A-DLU and back to the A-LTG. The test tone Ior the loop test is provided by the tone generator in the A-SU. AIter the successIul completion oI test the A- GPselects the Iree time slot to the SN and sends the seizure message to the CP. Also A-GP commands the A-SLMCP to set up the speech path in the SLCA. 6) In the next step the tone generator in the A-SU sends the dialing tone to the A SLCA. A code receiver in the A-SU is ready Ior the receipt oI the dialing digits. A subscriber hears this dial tone.The subscriber then dials the number and the A-SU receives the dialed digits. 7) The A-SU transIers received digit code to the A-GP. AIter the Iirst digit is received the A-GP disconnects the dial tone. The data received by the A-GP is then transIerred to the CP. 8) The CP then checks its database and checks whether the B-subscriber is idle. The CP identiIies the DLU, SLCA and the connection oI the B-subscriber selects one oI the two LTGs to which DLU is connected and iI the line is idle, marks the B-subscriber busy. 9) The CP determines a path through the SN Ior the connection between the A-LTG and B-LTG and sends the setup commend to the SGC. It also inIorms the B-LTG with the seizure command about the speech channels (A-LTG-SN, SN-B-LTG), B-port number etc. The B-LTG loops the assigned speech channels. The CP inIorms the A-LTG in a setup command about the zone and the partner`s side (port, speech, and channel) and causes the A-LTG to perIorm a cross oIIice check (COC) between A-LTG & B-LTG. With the aid oI a report the A-GP inIorms the B-GP about the successIul COC and connects the subscriber`s speech channels through the A-GS. So Iar the call has been setup Irom the B-LIU. However the connection Irom the B-LTG to the B-SUB is still missing. 10) Now the connection between the B-LTG and the B-SUB is setup. For setting the connection the same steps are Iollowed Irom 1 to 5. AIter step 5 the B-GP sends the ringing command to the B-DLUC. The B-DLUC instructs the SLMCP to apply the ringing voltage B subscriber. The BGP Iorwards a switch command to the B-GS to send the ringing tone to the A subscriber.The A subscriber receives the ringing tone Irom the B-SU. 11) The B subscriber accepts the call by liIting the handset. The B-SLCA detects the loop closure. The B-SLMCP scans the B-SLCA and recognizes that B subscriber wants to accept the call i.e. has gone oII-hook. The B-SLMCP reports the lop closure to the B-DLUC. The B-DLUC removes the ringing tone current and Iorwards the message to the B-GP. The B-GP disconnects the ringing tone and connects the speech through the B-GS. 12) The B-GP reports the answer to the A-GP. Due to this report the initiates the charging procedure. 13) Finally the connection is established. It seems that the process will take time but the experience shows that the connection is set up in Iew seconds. The A-GP stores the call charges and stores in one oI the registers and transIers to the CP at the end oI the call. The whole process involved in establishing requires interaction between the various parts oI the hardware as explained in steps. In the daily liIe establishing the call seems to very simple but the system required to establish this call involves a great complexity both in architecture and the process designed Ior call set up. Fig6)-block diagram of CCNC 4.1) SUBSCRIBER ADMINISTRATION Subscriber administration in the EWSD system includes: O Directory number administration O Analog subscriber administration O ISDN subscriber administration O Analog PBX administration O ISDN PBX administration Each subscriber is assigned Iields in the database which hold both the call processing inIormation and inIormation Ior subscriber data. Prior to creation oI a subscriber line, the corresponding Iields contain initial values. When data are entered using MML commands, the database is updated to make the new data available to call processing. It is also possible to modiIy existing data Iields, i.e. to add Iurther data or to modiIy or delete individual data items. II a subscriber line is canceled, all Iields are reset to their initial values and the port is then available Ior creation oI a new subscriber line. 4.2) DIRECTORY NUMBER ADMINISTRATION The conIiguration and maintenance oI directory numbers and other related Iunctions are perIormed only at the initial installation and commissioning oI the exchange or in the case oI expansions or modiIications. Following items are administrated in directory number administration. 1)LOCAL AREA CODE The local area code consists oI the national traIIic discrimination code and the actual local area code. Each local exchange is assigned at least one local area code. However, upto 50 local networks can be created with the corresponding 50 local area codes.The local area code must be speciIied in any MML command that contains a directory number Iound in a multiple directory number volume (required parameter). Each LAC is created with the command ENTR AREACODE. It may be assigned to one or several DLU (prerequisite Ior DLU stand alone service). DIRECTORY NUMBERS Directory numbers serve to identiIy subscribers. They may consists oI no more than 12 digits, including the local area code. Directory number can be created as a single directory number or as directory number blocks. Directory numbers are set up and deleted normally in the blocks oI 10,100 or 1000. It is also possible to create a single directory number. This is normally used as a pilot DN Ior PBX with direct inward dialing. Any directory number set up in this way is can be used as the identiIication oI subscribers or PBX lines The directory numbers are not activated until code points are created Ior them. The code point Ior a directory number block contains the common digit combination oI the block. Example: Corresponding to a block oI 100 consisting oI the directory numbers 272200&&272299 oI the code point 2722. For bulk connection oI subscribers it is possible to create subscribers in advance on a preparatory basis and then create the code point at the time oI connection.It is preIerable to choose short directory numbers Ior PBX lines because the extension number has to be transmitted as well as the local area code and PBX directory number. In case oI large PBXs, it is possible that not all oI the entire range oI numbers assigned to the PBX is needed. By means oI directory number conservation it is possible to restrict the Iirst digit oI the extension number, i.e. the tens group dialed aIter the PBX directory number. The remaining part oI this tens group that is partially assigned Ior a PBX directory number can then be created Ior other PBXs or other subscribers, and extended by another digit to increase the range oI numbers by a Iactor oI ten. 3)DIRECTORY NUMBER ATTRIBUTES The Ieature 'multiple local networks in one exchange¨ allows up to 50 diIIerent local networks to be operated in one exchange. In the case oI several complete local networks there are two categories oI local area codes: O independent local area codes. e.g. 089 and 088 O local area codes derived or ' split oII¨ Irom each other (i.e. with common digit sequences) e.g. 089 and 0898 and 08989. The administration must ensure that the directory number volume is unique. This means that a directory number (consisting oI local area code and subscriber directory number) may occur once in all local networks oI the exchange and in the entire network. A distinction is thereIore drawn between being unique in a country, unique in an exchange and unique in a local network. EWSD provides the tools and the procedures Ior this purpose. Unique and multiple directory number volume in case of several local networks in one exchange A directory number attribute can be used (MML command) to deIine whether the directory number volume Ior an exchange with several networks should be unique or multiple. II it is to be unique each subscriber directory number may occur only once in the exchange with several local networks. II it is to be multiple, a subscriber number may occur several times in the exchange, but oI course may occur only once per local network in the exchange. ,250 Unique directory number volume: Local area code Directory numbers 089 24711 (PBX block) 247120.......247129 (10s block) 2471300.....2471399 (100s block) 24714000...24714999 (1000s block) 088 24715 (PBX block) 247160.........247169 (10s block) 2471700.......2471799 (100s block) 24718000....24718999(1000s block) Multiple directory number volume: Local area code Directory numbers 089 24711 (PBX block) 247120......247129 (10s block) 2471300....2471399 (100s block) 24714000..24714999 (1000s block) 088 24711 (PBX block) 247120.........247129 (10s block) 2471300.......2471399 (100s block) 24714000....24714999 (1000s block) Ability to dial own local area code in the exchange A distinction must be drawn here between: O calls to the own local network in the exchange (local area code to which a subscriber is assigned by the administration) O calls to another local network in the exchange (local area code oI another local network in the exchange) As a general rule subscribers in an exchange are permitted to dial their own local area code Ior calls to their own local network, but it is not necessary. The administration also has the possibility oI using an MML command to disallow and allow again the Iacility Ior dialing the local area code Ior calls to subscriber`s own local network. II the directory number attribute Ior the directory number volume is 'unique¨, the local area code can be dialed Ior a call to the subscriber`s own local network or to another local network in the exchange. II the directory number attribute Ior the directory number volume is ' multiple¨, the local area code must be dialed Ior a call to another local networks in the exchange. Handling of emergency call areas in an exchange with multiple local networks Subscribers oI all the local networks in an exchange can have diIIerent emergency call areas assigned to them according to their geographical location although the same emergency call number is dialed. A separate emergency call area can be assigned to each local network. In the above Iigure, local network 1 has emergency call area 1 assigned to it with the emergency call number 110. Local network 2 has emergency call area 2 assigned to it with the emergency call number 110. Digit-zone conversion zoning dependent on originating local network) When subscribers in one local network dial into another local network in the same exchange, diIIerent charges may be demanded Irom the subscribers due to geographical location oI the local networks. Local network 1 Local network 1 Local network 1 Local network 2 Emergency call area 1 Emergenc y call area Fig(7) Subscriber A in Local network 1 dials into local network 3, belonging to zone 2. Subscriber B in local network 2 dials into local network 3, belonging to zone 1. Subscriber C in local network 1 dials into local network 1, belonging to zone 1. The originating local area code (local network index oI origin) is used Ior digit -zone conversion just as it is Ior digit destination area conversion. This means that zoning can be carried out Ior all the subscribers oI a local network without individual origin codes being necessary. This method is simple Ior operating personnel as the MML inputs are analogous to those Ior digit conversion. Remote control unit, RCU An RCU, consisting oI upto six DLUs (digital line units), can maintain the emergency service oI an exchange. The emergency service in an RCU is limited to one local network, however, iI an exchange has multiple local networks, care should be taken to ensure that several local networks are not serviced by one RCU. Local Network 1 Local Network 2 Local Network 3 Zone 1 Zone 1 Zone 2 Fig(8) 4.3) ANALOG SUSCRIBER ADMINISTRATOR A Subscrlber may only be creaLed lf Lhe followlng condlLlons have been meLŦ O @he dlrecLory number musL be ln Lhe range of exlsLlng dlrecLory numbers and may noL already be asslgned Lo anoLher subscrlberŦ O @he porL musL be ºnoL connecLed"Ŧ O @he Lype of clrculL found ln Lhe porL musL correspond Lo Lhe hardware requlred for Lhe subscrlber llneŦ SubsŦ daLa may be enLered whlle Lhe subscrlber ls belng creaLed (ck 5u8) or modlfled or deleLed aL a laLer daLe (MOu 5u8)Ŧ The subscriber may be assigned originating marks that are used routing and zoning. SemlŴpermanenL subscrlber daLa can be dlsplayed by enLerlng a MML command (ulSÞ Su8)Ŧ @ranslenL daLa can be dlsplayed by enLerlng command S@A@ Su8Ŧ SU8SCkI8Lk CLASSLS CI SLkVICLS @he followlng condlLlons musL be meL before classes of servlces may be enLeredť O @he Lype of clrculL musL be compaLlble Lo Lhe classes of servlcesŦ O @he llne caLegory musL be compaLlble Lo Lhe classes of servlcesŦ O @he classes of servlces musL be compaLlble Lo one anoLherŦ (eŦgŦ PoLllne lmmedlaLe and call walLlng ) @he dependencles and compaLlblllLy requlremenLs can be found ln Lhe relevanL commands ln Lhe LxCPťCML manualŦ @he modlflcaLlon of a subscrlber's dlrecLory number or equlpmenL number or equlpmenL number does noL affecL exlsLlng classes of servlcesŦ When a subscrlber ls canceledţ Lhe relevanL classes of servlces are also canceledŦ @he mosL lmporLanL subscrlber classes of servlces (subscrlber feaLures) are descrlbed hereŦ (4Ŧ3Ŧ1)CALL ICkWADING Call Iorwarding is a Ieature that may be assigned to a subscriber during setup or upon subsequent application. It allows calls that are destined Ior one subscriber (B1 called party) to be Iorwarded to another directory number(B2 called party). Three main diIIerent types oI call Iorwarding are available: O Call Iorwarding immediately All calls to the B1 called party are Iorwarded to the B2 called party regardless oI the status oI B1. The B1 called party may still make outgoing calls. O Call Iorwarding on busy All calls to the B1 called party are Iorwarded to the B2 called party iI the B1 directory number is busy. O Call Iorwarding on don`t answer All calls to the B1 called party are Iorwarded to B2 called party iI the B1 called party does not reply within a speciIied time. Call Iorwarding is usually activated and deactivated by the operator. II a subscriber wishes to use this service (subscriber input), proper authorization may be granted by the operator. Canceling the authorization and deactivating the diversion has no eIIect on an existing diverted call. Only one call can be diverted Irom a subscriber line at one time. Any Iurther calls directed to this B1 subscriber are given busy tone. B1 called B2 called party or operator or requested connection forwarded connection Fig(9) A calling party 'Operation¨ can have value(s) 'ACT(activation),DACT(deactivation), ENTR(entry oI directory no to which call will be diverted),ENTRAC( entry oI directory no. to which call will be diverted with activation .¨ Procedure Ior ACTIVATION/DEACTIVATION: Dial 114 Iollowed by the telephone number Ior which the call is to be transIerred. He will get the acceptance tone. Dial 115 and wait Ior acceptance tone. 4.3.2)TRAFFIC RESTRICTIONS IN THE OUTGOING DIRECTIONS This Ieature allows a subscriber to prevent all outgoing calls or all calls to a speciIic direction or to a speciIic zone Irom being made Irom his or her telephone. The Ieature covers the Iollowing: O service restrictions in the outgoing direction, Iully administration controlled. O service restrictions in the outgoing direction, administration registration, subscriber controlled. O service restrictions in the outgoing direction, Iully subscriber controlled and selected. The Iollowing terms have been used in this description: Destination : End exchange oI called subscriber. Zone : Geographical area containing all the end exchanges with the same tariII regulations as seen Irom the originating exchange TraIIic type : Calls to a particular destination. (DeIined using # DEST or # ZOPT command) Zone traIIic type : Calls to a particular zone. 4.3.2.1) MODE OF OPERATION Service restriction in the outgoing direction distinguishes between destination-related and zone- related restrictions. destination related and zone related restrictions can be entered and activated in the exchange independently oI each other. A restriction class can be assigned to a subscriber line. II a traIIic type or a zone traIIic type is assigned to an activated restriction class, call attempts to this destination or zone are rejected. The rejected calls can be diverted to an intercept service assigned to the traIIic type(e.g. tone, announcement etc.) A subscriber line can only have one restriction class activated at any time (either destination- related or zone related). Destination-related restrictions The administration can assign one or more (max. 15) traIIic types to each restriction class(these traIIic restriction classes are deIined using ENT# T#BLO command). CP call processing determines the destination and hence the traIIic type Irom the dialing inIormation. (a national, international, or intercontinental restriction etc. is recognized by the destination analysis). one-related restrictions The administration can assign one or more (max. 15) zone traIIic types to each restriction class (again using ENT# T#BLO command these classes can be deIined). From the dialing inIormation ' CP call processing¨ determines the zone, on the basis oI which a call is charged, and Irom this determines the zone traIIic type. This enables outgoing calls to be barred on the basis oI the zone. (A national, international or intercontinental restriction is recognised by the zone analysis). Zone related barring oI the out going calls takes place only iI zoning is carried out in a subordinate exchange. II zoning is carried out in a super-ordinate exchange, outgoing calls are not barred. 4.3.3)THREE PARTY CONFERENCE SERVICE 'Three party service with three way conversation¨ Ieature enables the subscriber to hold an existing connection while setting up another to a third subscriber. Three party conIerence service is perIormed in the group switch oI the calling party LTG. With this Ieature it is possible to- O switch between the Iirst and second connection O end one oI the connections and retain the other O set up a common speech path between all three subscribers A-SUB performs hook-flash ,gets dial tone and dial 3 1. Normal call set up A-SUB (COS= B-SUB in HOLD no more speech connection to A-SUB 2. A-SUB performs hook flash A-SUB gets dial tone 3. A-SUB sets up a call to second subscriber (C-SUB) C-SUB (ACTÌVE) A-SUB B-SUB C-SUB ACTÌVE ACTÌVE Fig(10) B-SUB In the Iigure(10), the mode oI operation oI three party service Ieature is explained. A calling party (A-SUB) with this Ieature can put his partner into waiting position and sets up another call to a diIIerent subscriber. This is called 'three party CALL status¨ The A-SUB establishes a three party conIerence Irom three party CALL status by perIorming a hook Ilash and dialing 3 aIter special dial tone. II either oI the two called parties (B-SUB or C-SUB) go on hook during an active three party conIerence they are released individually. II the A-SUB goes on hook, the complete three party conIerence is released. Fig(11) 4.3.4)MALICIOUS CALL IDENTIFICATION FEATURE The malicious call identiIication (MCI) Ieatures allow the origin oI malicious calls to be identiIied. The malicious call identiIication service is activated via the subscriber classes oI services. The Iollowing options are available: O Call Identification unconditional Malicious call data is saved Ior all incoming calls aIter call set-up has been completed. O call identification on request Malicious call data is only saved iI the called party activates identiIication dur during call set up (e.g. by perIorming a hook Ilash). None oI the possible options stated above oI MCI cause blocking oI the calling or the called party`s line. Both subscribers can be accessed Ior both incoming and outgoing calls immediately aIter an MCI connection. 4.3.4.1) FUNCTIONS INVOLVED IN MALICIOUS CALL IDENTIFICATION II the called party has been assigned the malicious call identiIication class oI service, malicious call data will be generated either automatically or upon request. This data record may contain the Iollowing: O date, time oI the day. O directory number inIormation and associated directory numbers. O calling party or called party trunk group number. O calling party or called party line number. O calling party or called party circuit identiIication code (CIC) and, as additional inIormation, network indicator (NI) and signaling point code (SP code) where there is networking with CCS7 signaling links. This data is stored in the main memory in a cyclic buIIer. Once the buIIer is Iull, the data is automatically transIerred to the call identiIication Iile on the magnetic disk. Operating personnel may transIer manually the data stored in the buIIer using the command T#NS BUFFE#. Data stored on the disk may be read out using display commands. With MCI, an MCI alarm is also signaled at the system panel in the EWSD exchange provided the MCI Ieature has been created with an MML command. 4.3.4.2) MALICIOUS CALL ADMINISTRATION CP CALL Process Buffer ÌCMAL SCOS= CALÌDREQ or SYP ENTR MALAD ALARM = MALREQ or Turn off: ACCEP CALÌD Ìf full or TRANS BUFFER: TYPE= MAL; ÌA.ÌCMAL (cyclic file) DÌSP MAL SEL MAL ENTR MALAD: DÌSP= MALREQ or MALÌMM, FEAT= DNDÌSP; Fig(12) Above diagram explains the various steps involved in the malicious call administration. 4.3.5)FIXED DESTINATION CALL HOT LINE) This Ieature allows a subscriber to set up a call to a speciIied number (destination directory number) simply by liIting the hand set. It comprises the Iollowing: O Feature 1, Iixed destination call, immediate, administration controlled. A call is set up to the destination number as soon as the subscriber liIts the hand set. O Feature 2, Iixed destination call, with time-out, subscriber controlled. A call is set up to the destination number iI the subscriber does not start dialing another number within a Iixed time. 4.3.5.1) MODE OF OPERATION The Iixed destination call Ieature means that the subscriber does not have to dial a number. The subscriber line has a destination number permanently assigned to it. The destination number can be up to 19 digits long and may not contain any special characters. It must be a complete number; a partial number is not possible. Entry oI a new number overwrites the previous destination number.Fixed destination calls are handled as normal calls. II a subscriber authorised to use the Ieature has not deIined a destination number, he or she is treated as a normal subscriber. 4.3.6)CALL WAITING A subscriber in a stable call is inIormed that another call is waiting. This subscriber is then able to interrupt the original call and accept the new one. Complete secrecy of communication between the two callers is matained. The description covers: O Feature 1, call waiting, indication controlled by the called subscriber, acceptance by clearing. The subscriber can accept a waiting call. At the same time, the existing connection is cleared down. O Feature 2, call waiting, indication controlled by the called subscriber, acceptance without clearing. The subscriber can accept a waiting call and simultaneously place the existing connection on hold. He/she can then switch between the connections (hold Ior enquiry, hold toggle), but only one connection is active at one time. Procedure Ior activation/deactivation: Dial 118 and get the acceptance tone similar to the engage tone but with a longer gap between the beeps. Dial 119 and get the acceptance tone. 4.3.6.1) TERMINOLOGY The Iollowing terms are used in this description. O Controlling party The subscriber authorised Ior the Ieature. (Waiting calls can be oIIered to this subscriber) O Original call The original connection between two subscribers, one oI whom has authorisation Ior call waiting (controlling party). O Waiting call Connection between the waiting party (new calling party) and the controlling party. O Talking connection The currently active connection between two parties in the talk state. (connection between controlling party and non controlling party who is on hold). O Held connection The currently inactive connection, having been placed on hold and not in talk state. O Hook Ilash A brieI interruption oI the subscriber loop made by tapping the switch hook Ior less than one second. 4.3.6.2) MODE OF OPERATION The controlling party can activate or deactivate the Ieature Ior his/her line. II the Ieature is activated and a user is involved is a stable(two party) call, he/she will be inIormed by a call waiting tone that another connection has been set up to the busy line. The call waiting time (ringing time) can be set by means oI MML commands (normally 30 seconds). The call waiting tone cannot be heard by the non-controlling parties. The incoming waiting call is treated as a ringing call (i.e. ringing tone, no call charge registration). Call waiting can be used Ior only one call at a time. Further call attempts will be rejected with the busy tone II a call is waiting, the controlling party can either continue the original call switch to the new two party call switch to a three party connection O Ignoring a waiting call The controlling party can ignore a waiting call and continue original two party call. O Call waiting with two- party call (Feature 1) Accept new call, clear original call The new controlling party can accept the waiting call. At the same time, the original call is cleared (new two party call) O Call waiting with three party connection (Feature 2) Accept new call, place original call on hold The controlling party can accept the waiting call and simultaneously place the original call on hold. This creates a three party connection, in which only two parties are able to talk to each other at any one time. O Hold Ior inquiry AIter the waiting call has been accepted in accordance with Ieature 2, the user can switch between the two connections. Only one connection is active at a time. The party with inactive connection is on hold and hears the hold tone. He/she cannot listen in to the active connection. O Clear down oI connections The subscribers in a three-party connection can disconnect at any time by going on-hook. II the controlling party disconnects, he/she will be called by the inactive connection (ring back). 4.3.7)ABBREVIATED DIALING You may be calling a Iew people Irequently.It is possible to program these numbers as abbreviated codes oI 1 or 2 digits.A maximum oI 20 numbers can be programmed Ior abbreviated dialing.It is ideal Ior STD/ISD. PROCEDURE: Step1 Select your short code Choose a short code Ior the number you dial Irequently e.g. '15' Ior the number xxxxxx. (iI it's std no. std code+xxxxxx) Step 2 Register short code Ior a telephone no. On your telephone dial 110 then the short code Iollowed by the subscriber's number i.e. dial 110 15 xxxxxx. You will shortly here an acceptance tone indicating that your code is registered. Step 3 To dial the number using abbreviated code Dial 111 then the short code to dial the number i.e dial 111 15 this will dial xxxxxx. To cancel or re-allot the same number dial 110 15 yyyyyy (new tel. no) this will store code 15 Ior new number yyyyyy overwriting the earlier no. xxxxxx. 4.3.8) AUTOMATIC WAKE-UP/REMINDER CALL SERVICE When you want to be given reminder at a speciIic time, all you have to do is to call the exchange and leave the time you want to be reminded. The Iacility allows you to initiate a call automatically by the exchange at a Iixed time speciIied by the user oI the telephone. Dial 116 (the registration code) Iollowed by the time you wish to be reminded or worken-up at 06.15am(06.15hrs), you will dial 1160615. Dial 117 (the cancellation code) Iollowed by the time you booked the call. 4.3.9)NUMBER/CALL HUNTING SERVICE II you have more than one telephone line, this Iacility is very helpIul Ior your caller. II the called line is engaged, your caller does not have to disconnect and dial other line(s). This Iacility automatically transIers the incoming call to whichever line is Iree. 4.3.10) CALLING LINE IDENTIFICATION PRESENTATION CLIP) The subscriber has to buy separately the CLIP display device Irom market. Using this Iacility you can see the number oI the calling party beIore liIting your telephone. Very useIul to trace malicious caller. However, the CLIP instrument shall be procured and installed by the users themselves. 4.3.11) CALLING LINE IDENTIFICATION CLI) ANNOUNCEMENT SERVICE Dial 164 and listen to the number oI the phone line that you have used to make the call. Very useIul when in doubt about your phone number. 4.3.12) PHONE BELL CHECK Dial 161 and aIter a Iew second replace the hand set. Your phone will ring very soon. UseIul Ior checking Iunctioning or adjusting volume oI bell oI your phone. 4.3.13) ELECTRONIC LOCKING FOR STD/ISD For 100° protection against improper use, you can lock your telephone electronically. Here, you only know the secret code. You can lock/allow Local, STD or ISD calls in many way viz. all calls allowed, only local calls allowed, only STD & Local calls allowed,all local calls barred etc. Register Secret Code Suppose you want to make 5555 your secret code. Follow this procedure to register this: Dial 123 5555 5555 then wait Ior the acceptance tone then disconnect. Your code is registered. Change secret code Suppose you want to change current code 5555 to 4444 then Dial 123 5555 4444 then wait Ior the acceptance tone then disconnect. Your new code(4444) is registered. Bar/Open Facilities using Secret Codeexample 5555) Bar STD/ISD calls Dial 124 5555 1 then wait Ior the acceptance tone then disconnect. Now STD/ISD calls will be barred . Open STD/ISD calls Dial 124 5555 0 then wait Ior the acceptance tone then disconnect. Now STD/ISD calls can be made. Open STD calls only Dial 124 5555 3 then wait Ior the acceptance tone then disconnect. Now STD calls can be made. Bar STD/ISD/manual trunck calls Dial 124 5555 2 then wait Ior the acceptance tone then disconnect. Now STD/ISD/manual trunck calls will be barred . (It will also bar calls to 95 level). Bar local calls Dial 124 5555 4 then wait Ior the acceptance tone then disconnect. Now localcalls will be barred .(applicable only iI STD Facility is available). Open local calls only Dial 124 5555 1 or 2 then wait Ior the acceptance tone then disconnect. Now Local calls can be made. 5.1) CONCLUSION Telecommunications sector is growing at a Iast rate. The dependence oI people on the telecommunications has also increased very much. For building reliable telecommunication systems a lot oI engineering and designing is required. An optimized system can only be designed aIter proper planning and consideration oI each and every Iactor that can aIIect working oI the system. The inIrastructure used Ior network elements in the network must also be capable oI meeting real time requirements like traIIic variations due to time oI the day (day or night) oI the network etc. For increasing the reliability and capability oI network elements the inIrastructure involved becomes very complex and sophisticated. Due to the rising complexity in the system it is desirable that the systems should be divided into modules or subparts. These modules or subparts will help in reducing the complexity oI whole system and limiting the complexity oI a particular subsystem to that part only. This kind oI approach can be seen in EWSD system where whole system is being divided into many subsystems. This also helps the switch designer while conIiguring the switch. In addition it also helps in increasing the Ilexibility oI the system in terms oI easy expansion whenever required. By making the individual network elements modular we can design and implement a complex network with much more ease. This makes whole network modular as network is nothing but the collection oI all these network elements. Thus the approach to design a network is to recognize the network elements and design parameters based on the needs required in the network and then start conIiguring the elements on the basis oI parameters given. From the Iirst part oI thesis we can easily recognize these approaches. As EWSD is a modular approach we can expand the capacity oI exchange by increasing the no. oI modules. For increasing the capacity we need not to change the whole design oI exchange. So EWSD plays a great role telecommunication. Sure, wireless phones oIIer you convenience, letting you talk Irom virtually any location. What you may not realize is that they can`t provide all the advantages oI landline phones. That`s why the FCC says, 'A combination oI landline and wireless phone use may be the right choice Ior you.¨ Landline phone service gives you: Reliability: You can count on constant connections, since power outages won`t aIIect your landline phone service. Safety: 911 operators receive your exact location automatically when you call whether you have the capability oI speaking or not. Cost Savings: Enjoy unlimited local calling without having to worry about minutes or extra charges. Dependable Quality: When was the last time your landline phone dropped an important phone call? Directory Listings: When you subscribe to landline phone service, your number is listed in the local phone book. Hometown Connection: When you need help, Hamilton Telecommunications is close by to provide local customer service. Plus, your communications dollars stay here to boost our local economy. 6.1) REFERENCES O http://www.alttc.bsnl.co.in/ O http://en.wikipedia.org/wiki/Mobile¸ad¸hoc¸network O http://www.bsnl.co.in/ O http://www.telecom.ntua.gr/~libero/svct2.pdI O http://education .icn.siemens.com/doc/pdIs/b0200¸001¸i06.pdI O http://www.sytechcorp.com/new¸site/SytechCorp/SyTechCorpXY/siemens.pdI