Simple and clearly ,Brief defined Terms which i learnt during My internship in PTCL. Further more if you have any problem you can E.mail me. hopefully will help you guys

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INTERNSHIP REPORT
SUBMITTED BY: Zawar -ul-Haq
Department of Information Technology

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PREFACE
This report is prepared under the shadow of University of Education Lahore, Multan Campus, whose
primary purpose is to familiarize the students of Information Technology with Switching & structure of
networkandtheirpractical implementation.InthisexpeditiononlyThe PTCLisbesteverplatformforthe
students.Inthe reportinitiallythereisintroductiontoPTCLanditsbrief descriptionalongwithitsservices
and products. Afterthat Telecommunication,typesof signalsand theirconversionisdiscussedindetail.
As major objective is switching so, in the report Switching and its types is explained briefly,additionally
difference betweencircuitswitchingandpacket switchingisclarified.ReportalsocontainISDN services,
provided by PTCL, NGN, Protocols of Networks, NMS and different major and vital role playing
componentsof hardware suchaDSLAM, MSAG,SoftswitchalongWithThe PowerSupplySystemof PTCL.
Zawar-ul-Haq
BS InformationTechnology

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ACKNOWLEDGEMENT
In the name of Allah Almighty who is most merciful, and who give me strength and chance to write this
internship report in a different way. I would like to extend my thanks to my Parents for their appreciation
and prays, seniors, colleagues, and teachers who assist me and put their efforts in every situation to enable
me to write this report.
I am Indebt specially, and would like to present my heartiest and most thanks to Mr. Irfan Aslam who
guided me in his different and unique style, without such heinous personality it was impossible for me to
write this report.
I would like to pay my regards to the HRM Department, Switching Department and all the employees, who
beard my Non-Professional attitude during internship.

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Table of content:
PTCL A-BRIEF DESCRIPTION…………………………………………..…............................04
Company Profile………………………………………………………………………………………….05
Telecommunication…………………………………………………………………………………….05
Signals………………………………………………………………………………….……………………..05
Analog to Digital Conversion……………………………………………………….………………05
Switching ………………………………………………………………………………………………......07
Circuit Switching……………………………………………………………………………………......07
Packet Switching……………………..………………………………………………………………….07
ISDN……………………………………………………………………………………………………………08
NGN……………………………………………………………………….…………………………………..09
NGN Layers…………………………………………………………..…………………………………….09
Soft Switch…………………………………………………………….……………………………………10
MSAG………………………………………………………………..………………………………………..11
DSLAM………………………………………………………..………………………………………………11
Protocols………………………………………………………………………………….…………………12
DTMF………………………………………………………………………………………………………….12
SS7…………………………………………………………….……………………………………………….13
H.248……………………………………………..…………………………………..….…………………..13
SIP……………………………………………………………………………………………………….……..13
NMS………………………………………………………………………………………………..………….14
AAA Server………………………………………………………………………………………………….15
Power Supply System………………………………………………………………………………….15
DSL……………………………………………………………………………………………………………..16

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PTCL A-BRIEF DESCRIPTION:
PTCL is megacorporation and a leading telecommunication authority in Pakistan. The policy
provides for the Federation of telephonic services nation-wide and is the country's backbone for
telecommunication infrastructure with the arrival of a dozen other telecommunication
corporations, with Telenor Corps and China Mobile Ltd. The Federation controls and operates
around 2000 telephone exchanges all over the country, providing fixed line network. Data and
backbone services such as GSM, CDMA, broadband Internet, and IPTV, wholesale is an
increasing part of its business.
Pakistan Telecommunication Company Limited
Type Public
Traded as PTC (KMI 30 Index)
Industry Telecommunications corporation
Genre Telecommunication
Founded August 14, 1947
Headquarters Islamabad, Islamabad Capital Venue, Pakistan
Products Wireless
Telephone
Internet
IPTV
Owner(s) Pakistan Government
Etisalat Telecommunications
Subsidiaries www.ptcl.com.pk

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COMPANY PROFILE:
PTCL is the largest telecommunications provider in Pakistan. PTCL also continues to be the largest
CDMA operator in the country with 0.8 million V-fone customers. The company maintains a
leading position in Pakistan as an infrastructure provider to other telecom operators and corporate
customers of the country. It has the potential to be an instrumental agent in Pakistan’s economic
growth. PTCL has laid an Optical Fiber Access Network in the major metropolitan centers of
Pakistan and local loop services have started to be modernized and upgraded from copper to an
optical network. On the Long Distance and International infrastructure side, the capacity of two
SEA-ME-WE submarine cable is being expanded to meet the increasing demand of International
traffic.
TELECOMMUNICATION:
Its combination of two words tele and communication, tele means far and communication means
exchange of information .So it’s a field where information/data/ or signals are sent on a distance
by using any media from one pace to other.
SIGNALS:
Signals are of two types:
Analog & digital
To send signals we before convert analog signals into digital form which is as follows:
ANALOGUE TO DIGITAL CONVERSION:
Sampling:
The first step in analog to digital conversation is sampling. The sampling operation converts
continuous analog signal/ waveforms into a sequence of discrete samples. Samples are very narrow
pulses. Sampling should be sequence wise. The telephone signal is sent to sampling switch via low
pass filter, which suppresses higher frequencies than sampling frequency (8000 Hz). The sampling
switch goes through all the time slots whether they have information or not. Time for sampling
switch for complete rotation = 125 µsec. The output of sampling switch is Pulse amplitude
modulation (PAM)
Signal.
LOW PASS
FILTER
SAMPLING
SWITCH

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Pulse Amplitude Modulation (PAM):
The sampled signal is said to be pulse amplitude modulated as it contains train of pulses. Whose
amplitudes are modulated by an original signal? It is not a total digital signal but a step towards
digital process. The amplitude of each sample has its specific value known as amplitude step.
Quantization:
Assigning some value to each sample is quantizing. The whole range of amplitude values are
divided into quantizing intervals. The quantizing intervals are divided into 16 parts +1 to +8 and -
1 to -8. The boundary of adjacent quantizing intervals is called decision value or quantizing step
on the transmit side several amplitude values falls in the same quantizing interval but on receive
side, we have to recover one signal value corresponds to the midpoint of quantized interval. This
results in discrepancy on the receive side equal to half the quantized interval called quantizing
noise/ discrepancy. The quantizing noise is reduced by two ways
The quantizing noise is minimized by.
(a) Increasing the number of quantizing intervals.
(b) Q intervals are made small e.g. 256 quantizing intervals +1 to +128 and -1 to -128
positive and negative intervals.
• Types of Quantizing:
• Linear Quantizing (All the quantizing intervals are of equal size).
• Non Linear Quantizing (The quantizing values are not equally divided.
Non-linear quantizing have the advantages of that low and high amplitude signal are to add or
subtract less noise value. Non-linear quantizing is called commanding.
De-Multiplexing:
On the receive side the individual PCM signals are received from the TDM signal. The 8-bit PCM
words are distributed to appropriate outputs.
Decoding:
On the receive side to each 8-bit PCM word a signal amplitude is allocated. It corresponds to the
midpoint of the particular quantizing interval. A pulse amplitude modulated signal is produced
again
Filtering:
To recover original analog signal from PAM signal, the PAM signal is passed through Low pass
filter.

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SWITCHING:
The process of making a connection between telecommunication devices, so that they
communicate with each other or a switch is a device that channels incoming data from any of
multiple input ports to the specific output port that will take the data toward its intended
destination.
Circuit Switching:
Each connection through a circuit switched network results in a physically communication channel
being set up through the network from the calling to the called subscriber equipment. The circuit
may pass through the number of telephone exchanges in different parts of the country. At each
stage a switch is physically closed until a link is made between the two ends. The physical circuit
will remain for the duration of the call and at this time it is said to be BUSY.
Packet Switching:
In packet switching data networks, all user data to be transmitted is first divided into one or more
units, called packets, by the source DTE. These packets are of varying lengths, and reach packet
is assigned an address and the necessary control information. In each switching node, packets are
received, stored briefly, and passed on to the text node. Packets includes both the source and the
destination DTE network addresses.

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Difference b/w Circuit switching Packet switching:
Circuit Switching
Packet
Switching(Datagram type)
Packet Switching(Virtual Circuit
type)
Dedicated path No Dedicated path No Dedicated path
Path is established for entire
conversation
Route is established for each
packet
Route is established for entire
conversation
Call setup delay packet transmission delay
call setup delay as well as packet
transmission delay
Overload may block call
setup
Overload increases packet
delay
Overload may block call setup and
increases packet delay
Fixed bandwidth Dynamic bandwidth Dynamic bandwidth
No overhead bits after call
setup
overhead bits in each packet overhead bits in each packet
ISDN (Integrated Services Digital Network):
ISDN is a worldwide digital communications network evolving from existing telephone services.
The goal of ISDN is to replace the current telephone network which requires digital−to−analog
conversions with facilities totally devoted to digital switching and transmission, yet advanced
enough to replace traditionally analog forms of data ranging from voice to computer transmissions,
music, and video.
ISDN is built on two main types of communications channels:
 B channel, which carries data at a rate of 64 Kbps (kilobits per second).
 D channel, which carries control information at either 16 or 64 Kbps.
Computers and other devices connect to ISDN lines through simple, standardized interfaces. It
provides users with faster, more extensive communications services. Most recently, ISDN service
has largelybeen displacedby broadband internet service,such as xDSLand CableModem service.
These services are faster, less expensive and easier to set up and maintain than ISDN. Still, ISDN
has its place as backup to dedicated lines and in locations where broadband service is not yet
available.

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NGN:
What is NGN?
Next Generation Network (NGN) is a service oriented network. NGN provides integration of
voice, data, fax, and video services.
In broad sense it refers to the next generation integrated network that adopts new technologies
extensively, focuses onIP,andprovidesvoice,data,andmultimediaserviceatthe same time.
NGN layer Architecture:
Access Layer:
It is the lowest layer in the model. It supports infrastructure for access of end user devices, like
wireless or standard telephones, mobile or desktop computer etc.to transport network and vice
versa. In access layer there are different types of gateways are installed for the direct connection
of users to the NGN. These gateways are as follows:
 Access Gateway (MSAG or MSAN)
 Signaling Gateway (SG)
 Trunk Gateway (TG)
 Integrated Access Device (IAD)
 Broadband Gateway (BGW)
 Wireless Gateway (WG)
 Media Gateway (MSG)
MEDIA GATEWAY
It converts ISDN (SS7) to NGN (H.248).It is actually a bridge that connects older networks to
NGN
Application layer
Control layer
Core layer
Access
layer

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Core layer:
Its use is to transfer between nodes of network. It is consisting from one or from multiple high-
speed backbone packet switched networks. It is possible to serve to a flows of different character
with different requirements on quality of transfer (delay, data loss).
Control layer:
Main task of management layer is to control other layers. It is liable for correct functioning of
management of transport layer (MGW/SGW). It controls service calling (application layer) and
also manages user profiles (access layer).
Application layer:
It is also common to call it a service layer, because it merger so called application servers and a
media servers (platforms for diffusions of content).
 We define three models of service provision:
 Web services inspired by internet and by distributed intelligence
 Services based on functions of servers in management layer with centralized
intelligence
 Services offered in network mediums of other operators.
SOFT SWITCH:
ZXSS10 SS1b soft switch control equipment is the core control equipment of ZTE soft switch
system, located on the control layer of soft switch network. Through completely separated service
and call control as well as completely separated call control and bearer, it performs functions of
call control, media gateway access control, resource allocation, protocol processing, routing,
authentication, charging, etc. It forms a relatively independent service system. The open service
architecture continuously fulfills user’s service requirements, enhances the comprehensive
competitiveness of operation network, and achieves sustainable development.
ZXSS10 SS1b is a carrier-class product which fully meets telecom operation requirement on
reliability and availability.

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ZTE ZXSS10 SS1b --- A Carry-class soft switch Core Control Equipment (NGN)
MSAG (Multi-Service Access Gateway):
MSAG is also known as MSAN (Multi-Service AccessNode) inZTE.It isa device typicallyinstalledina
telephone exchange or distribution cabinet, which connects customer telephone lines to the core
network. Typically MSAG consists of batteries with rectifiers, optical transmission and copper
distribution frame.
CARDS IN MSAG:
 GELC (Giga bit Ethernet Line Card) for IPTV,DSL and Voice.
 ALC (Analog Line Card) only for voice
 ODIT for extensions of line
 GISB control card for GELC
 GISE control card for ALC
DSLAM (Digital subscriber line access multiplexer):
A Network device at central office of telecom it receives signals from multiple customer DSL
connections and puts signals on a high speed backbone line by using multiplexing techniques.

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PROTOCOLS:
There are following protocols used in NGN:
DTMF SS7 H.248 SIP
DTMF:
DTMF is a signalingsystemforidentifyingthe keysorbettersay the number dialed on a pushbutton or
DTMF keypad. The early telephone systems used pulse dialing or loop disconnect signaling. This was
replaced bymulti frequency (MF) dialing. DTMFisamulti-frequency tonedialingsystemusedbythe push
buttonkeypads intelephoneandmobilesetstoconvey the numberorkey dialedbythe caller. DTMFhas
enabledthe longdistancesignalingof dialednumbers invoicefrequency range overtelephonelines. This
has eliminated the need of telecom operator between the caller and evolved automated dialing in the
telephoneswitchingcenters.
DTMF (Dual tone multi frequency) as the name suggests uses a combination of two sine wave
tones to represent a key. These tones are called row and column frequencies as they correspond to the
layoutof a telephone keypad.
A DTMF keypad (generator or encoder) generates a sinusoidal tone which is mixture of the row and
column frequencies. The row frequencies are low groupfrequencies. The column frequencies belongto
high group frequencies. This prevents misinterpretation of the harmonics. Also the frequencies
for DTMF are so chosen that none have a harmonic relationship with the others and that mixing the
frequencies would notproduce sumorproductfrequenciesthatcould mimicanothervalidtone. Thehigh-
group frequencies (the columntones)are slightly louderthanthe low-grouptocompensate forthe high-
frequency roll off of voice audiosystems.
The row and column frequencies correspondingtoa DTMF keypad have beenindicated inthe figure.

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SS7 (Signaling System 7):
Common Channel Signaling System No.7 (SS7 or C7) is a global standard for telecommunications
defined by the International Telecommunication Union (ITU) Telecommunication Standardization
Sector (ITU-T). The standard defines the procedures and protocol by which network elements in
the public Switched telephone network (PSTN) exchange information over a digital signaling
network to effect wireless (cellular) and wire line call setup, routing and control. The ITU
definition of SS7 allows for national variants such as North America’s American National
Standards Institute (ANSI) and Bell Communications Research (Telcordia Technologies)
standards and Europe’s European Telecommunications Standards Institute (ETSI) standard.
The SS7 network and protocol are used for:

 Wireless services such as personal communications services (PCS), wireless roaming and
mobile subscriber authentication.
 Local number portability (LNP).
 Toll-free (800/888) and toll (900) wire line services.
 Enhanced call features such as call forwarding, calling party name/number display and
three-way calling.
 Efficient and secure worldwide telecommunications.
H.248:
The H.248 feature provides a gateway control interface between the PGW 2200 and the VXSM
gateways. It supplements the MGCP protocol. This new interface is based on the ITU-SG16/IETF
specification of H.248 which defines a decomposed gateway architecture.
This architecture is composed of:
• A media gateway controller (MGC) and the media gateways (MGs)
• Distributed call control functionality between an MGC (an intelligent entity that manages the
establishment and tearing down of calls) and an MG (a simple entity that responds to the MGC
requests and independently processes media streams)
SIP:
 SIP is end-to-end, client-server session signaling protocol
 SIP’s primarily provides presence and mobility
 Protocol primitives: Session setup, termination, changes
 Arbitrary services built on top of SIP

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NMS (Network Management System):
The integrated network management system provides centralized, unified network management
for all ZTE NGN products including soft switch series such as: ZXA10 MSAN/MSAG, ZXA10
PON, ZXDSL series, terminal series, ZXR10/ZXB10/ZXE10 series ZXWMN HLR and so on.
Functionality:
 Topology and view management
 Fault management
 performance management
 Configuration Management
 Report management
 Policy managements
 Version management
 Diagnose test management
 Log management
 Security management
 MIB management
Characteristics:
 Unified platform: Operating, maintaining and managing various NEs on a Unified
platform in a centralized way.
 Expandable platform: Based on J2EE, it is an expandable platform to add more new NE
management and new functions.
 Multiple types of OS and DB: It supports multiple operation system such as windows and
UNIX. It can run on multiple DBMS, such as SQL server.
 Powerful topology management: it provides the graphical diagram of the whole network,
including all the nodes and links. All operation can be done via topology view.
 Powerful fault analysis: Provides fault correlation analysis, such as alarm delay, alarm
count, alarm restraint, alarm merger.
 Reliability: Supports out-of-band and in-band management modes and provides hot-
backup.
 Security: Provides privileged access control and log records.

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AAA SERVER:
A server which performs Authentication, Accounting, Authorization in central office of
telecommunication office.
 Authentication: Eithers the user being connected have permission to server, thus server
checks user name password or not, if it contain then that is authenticated by the AAA
server.
 Authorization: if user name and password is authenticated then user gets authorization from
server to be on internet.
 Accounting: Server performs accounting and provides facility of billing of each customer.
POWER SUPPLY SYSTEM OF PTCL:
PTCL uses –ve polarity of voltages, which have several benefits:
 Contamination reduces.
 Employees remain safe during field work.
 Easy to handle voltages.
Structure includes ZXDu 68 power supply system, which convert 240v coming from Main supply
into 48v of DC containing –ve polarity.
DSL:
Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are
used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL
is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly
installed DSL technology, for Internet access. DSL service can be delivered simultaneously
with wired telephone service on the same telephone line. This is possible because DSL uses
higher frequency bands for data. On the customer premises, a DSL filter on each non-DSL outlet
blocks any high-frequency interference to enable simultaneous use of the voice and DSL services.
The leading DSL technologies being deployed today include:
HDSL - High Bit-Rate Digital Subscriber Line:
The HDSL provides a symmetric connection, that is, upstream speeds and downstream speeds are
the same, and range from 1.544 Mbps to 2.048 Mbps at a distance of 12,000–15,000 feet.
Symmetric connections are more useful in applications like videoconferencing, where data sent
upstream is as heavy as data sent downstream. HDSL-II, which will provide the same transmission
rates but over a single copper-pair wire, is also round the block.

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SDSL - Symmetric Digital Subscriber Line:
SDSL supports symmetric (equal downstream and upstream) data transmissions up to 1.54 mbps.
VDSL-Very High Bit-rate Digital Subscriber Line:
VDSL is the fastest of all xDSL flavors and provides transmission rates of 13–52 Mbps
downstream and 1.5–2.3 Mbps upstream over a single copper-pair wire, at a distance of 1,000–
4,500 feet from the service provider’s premises.