GSM technology was developed to provide a pan-European mobile phone standard. It utilizes a cellular network structure with frequencies divided into channels. The presentation covered the history and development of GSM, including its architecture and call flow. Key aspects like the SIM card, frequency bands, wireless concepts and cellular structure were explained. The layers of the GSM system like physical, data link and network layers were defined. Signaling and control channels such as BCCH, CCCH and DCCH play important roles in network operations.

1. PRESENTED BY - AMAN RAJ
- KIIT UNIVERSITY
SCHOOL OF COMPUTER ENGINEERING
DATE – 09/06/2015
MENTOR – ANURAKAR MISHRA
NSS ENGINEER
( ERICSON PATNA)

2. GSM TECHNOLOGY

3. GLOBAL SYSTEM FOR
MOBILE COMMUNICATION
Points covered
• History of GSM technology
• Definition of GSM
• Basic definition of terms used in GSM
• GSM architecture
• Call flow
• Present scenario of GSM

4. HISTORY OF GSM
The idea of the first cellular network was brainstormed in
1947
It was intended to be used for military purpose as a way of
supplying troops with more advanced forms
Of communication
From 1947 -1979 several different forms of brodcasting
technology emerged
• USA began to develop AMPS(advance mobile phone
service) network
• European countries were developing their own forms of
communication

5. DEVELOPMENT OF GSM
Europeans quickly realized the disadvantages of each
European country operating on their mobile network, it
prevents cell phone use from country to country within
Europe
For the purpose of rectifying the situation the conference of
European posts and telegraphs(C E P T)
Assembled a research group with intentions of researching
the mobile phone system in Europe
Group called group special mobile (GSM)
For the next 10 years GSM group outlined standards
Researched technology and designed a way to implement pan
European mobile phone network

6. IMPLEMENTATION OF GSM
In 1989 work done by GSM was transferred to European
telecommunication standard institute
(ETSI)
GSM new name was given global system mobile
telecommunication
In 1991 commercial service of GSM network had begun
In 1993 there were 36 GSM networks in over 22 countries
Till now usa was using old analog AMPS network and tdma
In October 2001 ,cingular the first to anounce to switch to
3g GSM network involved more then 22 million customers switching
from tdma to GSM network
In 2005 cingular stopped new phone activation on TDMA ,began
Selling only GSM service

7. GSM FREQUENCY STANDARD WORLDWIDE
GSM-900 AND GSM-1800
Standard used mostly worldwide, frequency where European phones
operate on as well as Asia and Australia
GSM-850 AND GSM-1900
Used primarily by usa, also standard for Canada, countries in Latin and
south America
Cingular network operate on GSM-850
T-Mobile operate on GSM-1900
T mobile has roaming agreements with cingular
Meaning in case no service at GSM-1900,the phone will switch to GSM-
850 and operate on cingular network
GSM-400
Least popular of the bunch and rarely used

8. WHICH PHONE OPERATES ON WHICH NETWORK
There are four different frequencies that GSM phones operate on,it is
important to purchase your phone from cell phone company, must
match with the frequency of the service provider we use
issues arises when we buy a cell phone internationally
• DUAL BAND PHONE
Operating on two frequency any two
• TRI BAND PHONE
Operating on three frequency
• QUAD BAND PHONE
Operating on four frequency

9. DEFINITION OF GSM
Global system for mobile communication is an open
Digital cellular technology used for transmitting mobile voice
and data services
• GSM supports voice calls & data transfer speed up to
9.6kbps
• Allows travellers to access the same mobile service at home
or abroad
• It enables individual to reach via same mobile number over
219 countries
• GSM network covers almost 90% of world population

10. S I m
subscriber identity module

11. WHAT IS SIM
A sim card known as a subscriber identity module, is a subscriber
identity module application on a smartcard that stores data for GSM –
CDMA cellular telephone subscribers
Such data includes user identity, network authorization data, personal
security keys, contact lists and stored text messages
Security features include authentication and encryption to protect data
and prevent eavesdropping
A smart card with subscriber identity module application is generally
known as simcard
When a simcard is viewed as a smartcard, it opens up security
possibilities that resonate far beyond mobile world

12. FUNCTIONS OF SIM CARD
IDENTIFICATION
Identification of a subscribe::the IMSI programed on the sim card is the
identity of the subscriber
Each IMSI is mapped to a mobile number and provisioned on the HLR to allow
a subscriber to be identified
AUTHETICATION
Here we use authentication algorithm on the sim card
A unique response is provided by each subscriber based on
IMSI,KI(STORED ON SIM)::RAND (PROVIDED BY NETWORK)
By matching this response with values computed on the network a legal
subscriber is logged on and now he can use the services of the mobile service
provider
STORAGE
To store phone number and sms
APPLICATION
The sim tool kit or GSM 11.14 standard allows creating application on the sim
to provide basic info on demand like chatting

13. WHY SIM CARD IS SECURE
SIMCARD IN REALITY IS A MASS MARKET SMARTCARD WITH SUBSCRIBER
IDENTITY MODULE
SMART CARD IS VERY SECURE
• SECURE LOADING OF APPLICATION
• SECURE DATA STORAGE FOR APPLICATION DATA
• SECURE CRYPTO OPERATION SUPPORT
PRESENCE OF CRYPTOGRAPHIC ALGORITHM AND SECRET KEY IN SIM CARD
MAKES THE SIM CARD SECURE
PIN
PERSONAL IDENTIFICATION NUMBER
2 PINs EXISTS(PIN1 & PIN2)
LIMITED ATTEMPT OF PIN ACESS
PUK
PIN UNBLOCKING CODE
RESETTING PUK RESETS PIN AND ATTEMOT COUNTER
TOO MANY ATTEMPTS ON PUK BLOCKS USE PERMANENTLY

14. TWO WAYS OF STORING DATA IN SIM
As GSM files
The data used for telco and GSM operation are all stored over files
Telco operator can change the data through RFM in secure channel
As application data
M check STORES ALL ITS SECURED ENCRYPTED INFORMATION WITHIN
APPLICATION DATA
Data on sim is protected by administrative keys which are in
hexadecimal and it has been proved that compromising the security of
sim requires enormous supercomputing ability
And lots of time to crack a single card
We can conclude that sim card is so secure that it is ideal for banking
operation to be ported on.

15. wireless system

16. MEANING OF WIRELESS
Wireless is defined as having no wires
In networking terminilogy,wireless is term used to describe any
computer network where there is no physical wired connection
between sender and receiver
Network is connected by radio waves or microwaves to maintain
communication
Wireless networking utilizes specific equipment such as nic and
routers in place of wires

17. 1G TECHNOLOGY
• Refers to first generation of wireless telephone
technology
• Introduced in 1980 and completed in 1990
• Speed 2.4kbps
• Allows voice call in one country
• Uses analog signal
• Amps was first launched in usa in 1G mobile system
Drawbacks of 1G
• Poor voice quality
• Poor battery life
• Large phone size
• No security
• Limited capacity

18. 2G TECHNOLOGY
• 2G technology refers to 2nd generation based on GSM
• Launched in Finland in 1991
• Uses digital signal
• Data speed was 64kbps
• Enables services such as text messages picture messages
& MMS(multi media message)
• Better quality and capacity
Drawbacks of 2G
• Requires strong digital signal to help mobile phones work,
no network coverage, weak digital signal
• Unable to handle complex data such as videos

19. 3G TECHNOLOGY
• Introduced in year 2000
• Data transmission speed increased from 144kbps-2mbps
• Generally called as smart phones with increased bandwidth
and data transmission rate to accommodate web based
application
• Faster coomunication,send receive large email
,High speed web, more security, video conferencing,3d
games,mobile tv
Drawbacks of 3G
• Expensive fees of 3G licenses services
• Expensive 3G phones
• Large cell phones
• High bandwidth requirement

20. 4G TECHNOLOGY
• Started from late 2000
• Capable of providing up to 1gbps speed
• One of the basic term used to describe 4G is magic
• Mobile multimedia, global mobility support,
integrated wireless solution, customized personnel
service
Drawbacks of 4G
• Battery use is more
• Hard to implement
• Complicated hardware

21. 5G TECHNOLOGY
• Started in 2010
• Complete wireless communication
• High speed & high capacity
• Support interactive multimedia
• 5G is more effective and more attractive

22. EVOLUTION OF TECHNOLOGY

23. GSM Concepts -
Cellular Structure
Cellular
Networking technology
that breaks geographic
area into cells shaped like
honey comb
Cell
Is the radio coverage
area of one base
transceiver station
1
2
3
4
5
6
7
6
7
2
1
5

24. • Frequency band
• uplink 890 - 915 m h z
• Downlink 935 – 960 m h z
• Duplex frequency spacing 45mhz
• Carrier separation 200 k h z
• Frequency channels 124
• Time slots /frame(full rate)8
• Voice coder bit rate 13kbps
• Modulation g m s k
• Air transmission rate 270.833333 kbps
• Access method FDMA/TDMA
• Speech coder RPE-LTP-LPC
GSM SYSTEM SPECIFICATION

25. GSM TECHNOLOGY LAYERS
7-layer osi model
• ISO
– International standards organization
OSI
– Open systems interconnect
OSI model background
• Introduced in 1978 and revised in 1984
• Formulates the communication process into structured layers
• There are seven layers in the model, hence the name the 7-layer
model
• The model acts as a frame of reference in the design of
communications and networking products

26. THE LAYERED APPROACH TO
COMMUNICATION
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical

27. 7.Application layer
• Purpose
– User application to network service interface
• Examples
– File request from server
– E-mail services
– Etc.
• General network access
• Flow control
• Error recovery
6. Presentation layer
• Purpose
– Formats data for exchange between points of communication
• Ex: between nodes in a network
• Example:
– Redirector software
• Formats for transmission to the server
• Protocol conversion
• Data translation
• Encryption
• Character set conversion
• Expansion of graphics command
5. Session layer
• Purpose
– Oversee a communication session
• Establish
• Maintain
• Terminate
• Performs name recognition and related security
• Synchronization between sender and receiver
• Assignment of time for transmission
– Start time
– End time etc.

28. 4. Transport layer
• Purpose
– Repackage proper and efficient delivery of packages
• Error free
• In sequence
• Without duplication
• Example
• For sending data
– Repackage the message to fit into packets
• Split long messages
• Assemble small messages
• On receiving data
– Perform the reverse
– Send an acknowledgment to the sender
• Solve packet problems
– During transmission and reception
3. Network layer
• Purpose
– Addressing and routing the packets
• Example application at the router
– If the packet size is large, splits into small packets
• Purpose
– Addressing and routing the packets
• Example application at the router
– If the packet size is large, splits into small packets

29. 2. Data link layer
• Purpose
– Manages the flow of data over the physical media
• Responsible for error-free transmission over the physical media
• Assures error-free data submission to the network layer
• Point of origin
– Packages data for transmission over physical line
• Receiving end
– Packages data for submission to the network layer
• Deals with network transmission protocols
– Ieee 802. Protocols
1. Physical layer
• Purpose
– Deals with the transmission of 0s and 1s over the physical media
• Translation of bits into signals
• Example
– Pulse duration determination
– Transmission synchronization
– Etc.
• Encode bits into signals
– Carry data from the h higher layers
• Define the interface to the card
– Electrical
– Mechanical
– Functional
– Example: pin count on the connector

30. SIGNALING SYSTEM – (SS7)
• Common channel signalling system no. 7 (i.E., SS 7or 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 signalling network to effect wireless (cellular) and
wire line call setup,
• Routing and control. The itu definition of SS7 allows for national variants such
as the American
• National standards institute (ANSI) and bell communications research
(telcordia technologies)
• Standards used in north America and the European telecommunications
standards institute
• (ETSI) standard used in Europe.

31. CONCEPT OF E1….
1 e1 = 8000 frames / sec
1 frame = 32 timeslots
1 timeslot = 8 bits
E1 (2048 kbps) = 8000 frames/sec
X 32 timeslots/frame
X 8 bits/timeslot
= 8000 frames/sec
X 256 bits/frame
= 2048000 bits/sec

32. E1 STRUCTURE
1ST FRAME 2ND FRAME 3RD FRAME 8000TH FRAME
32 TIMESLOTS / FRA0TH 1ST 2ND 3RD 31ST
1ST 2ND 8TH7TH6TH5TH4TH3RD
8 BITS / TIMESLO
8000 FRAMES / SEC

33. CHANNEL CONCEPTS….
• Physical channel:
• One timeslot of a tdma-frame on one carrier
• Is referred to as a physical channel.
• There are 8 physical channels per carrier in
• GSM,channel 0-7(timeslot 0-7)
• Logical channel:
• A great variety of information must be
• Transmitted between bts and the MS, for e.g.
• User data and control signaling. Depending
• On the kind of information transmitted we
• Refer to different logical channels.These logical
• Channels are mapped on physical channel.

34. LOGICAL CHANNELS ON AIR INTERFACE
LOGICAL
CHANNELS
COMMON
CHANNELS
DEDICATED
CHANNELS
BROADCAST
CHANNELS
COMMON
CONTROL
CHANNELS
DEDICATED
CONTROL
CHANNELS
TRAFFIC
CHANNELS
FCCH BCCHSCH SDCCH SACCH FACCH
PCH AGCHRACH TCH/F TCH/EFRTCH/H

35. Broadcast channels BCH
• Broadcast channel-BCH
– Allowed one arfcn & is on all the time in every cell. Present in TS s 0 and other 7 TS used by TCH.
• Frequency correction channel-FCCH
• To make sure this is the BCCH carrier.
– Allow the m s to synchronize to the frequency.
– Carries a 142 bit zero sequence and repeats once in every 10 frames on the BCH.
• Synchronization channel-SCH
– This is used by the m s to synchronize to the TDMA frame structure within the particular cell.
– Listening to the s c h the m s receives the tdma frame number and also the BSIC ( in the coded part- 39
bits).
– Repeats once in every 10 frames.
Common control channels CCCH
• CCCH
– Shares ts-0 with bch on a multiframe.
• Random access channel-RACH:
– Used by mobile station for requesting for a channel. When the mobile realizes it is paged it answers by
requesting a signaling channel (SDCCH) on r ach. RACH is also used by the MS if it wants to originate a
call.
– Initially MS doesn’t know the path delay (timing advance), hence uses a short burst (with a large guard
period = 68.25 bits).
– M s sends normal burst only after getting the timing advance info on the SACCH
– It is transmitted in uplink point to point.
• Access grant channel-AGCH
– On request for a signaling channel by MS the network assigns a signaling channel( SDCCH) through
AGCH. AGCH is transmitted on the downlink point to point.
• Paging channel-PCH
– The information on this channel is a paging message including the m s’s identity(IMSI/TMSI).This is
transmitted on downlink, point-to-multipoint.

36. Dedicated control channels-dcch
• Stand alone dedicated control channel(SDCCH)
• A g c h assigns SDCCH as signaling channel on request by MS .The MS is informed about
which frequency(ARFCN) & timeslot to use for traffic.
• Used for location update, subscriber authentication, ciphering information, equipment validation
and assignment of TCH.
• This is used both sides, up and downlink point-point.
• Slow associated control channel-SACCH
– Transmission of radio link signal measurement, power control etc.
– Average signal strengths(RXLEV) and quality of service (RXQUAI) of the serving base
station and of the neighboring cells is sent on SACCH (on uplink).
– Mobile receives information like what TX power it has to transmit and the timing advance. It
is associated with TCH or SDCCH
• Fast associated control channel-FACCH
– Used for hand over commands and during call setup and release. FACCH data is sent
over TCH with stealing flag set
– Traffic channels-tch
• TCH carries the voice data.
• Two blocks of 57 bits contain voice data in the normal burst.
• One TCH is allocated for every active call.
• Full rate traffic channel occupies one physical channel(one TS on a carrier) and carries voice
data at 13kbps
• Two half rate (6.5kbps) TCH can share one physical channel.

37. C D M A GSM
• global system for mobile
communication
• sim storage type
• dominant standard worldwide
except us
• G p r s/e/3g/4g/l t e
• every cell has corresponding
network tower which serves
mobile phones in that area
• most accessible
• multiple(850/900/1800/1900)
• sim specific. User has option to
select handset of his choice
C d m a vs GSM
• code division multiple access
• internal memory storag e type
• global market 25%
• dominant standard in us
• data transfer eddo/3g/4g/l t e
• international roaming less
accessible
• frequency band single(850 m h
z )
• network service ,handset
specific

38. GSM ARCHITECTURE

39. TERMS USED IN GSM
Mobile station(MS)
The mobile station (MS) consists of the physical
equipment used by PLMN
Subscriber to connect to the network
It comprises the mobile equipment(ME)and sim
The me forms part of mobile termination (MT)
depending upon the application and the services
may also include various kind of terminal
equipment (TE) & terminal adapter(TA)

40. COMPONENTS OF MOBILE STATION
Subscriber identity -MSISDN
• The MSISDN is a GSM directory number which uniquely
identifies a mobile subscription in the public switched
telephone network (PSTN).
• Calls will be routed from the PSTN and other networks
based on the mobile subscribers’ MSISDN number.
• MSISDN= CC + NDC + SN
– CC= country code (91)
– NDC= national destination code(98370)
– SN= subscriber number (12345)

41. INTERNATIONAL MOBILE
SUBSCRIBER IDENTITY [IMSI]
• Subscriber always identified within the GSM network by
the IMSI
• This is used for all signaling in the p l m n stored in s I m
and H L R/V L R
• The I m s i consists of three different parts
– M NC = mobile network code(2 digits)
– M CC = mobile country code(3 digits)
– MSIN = mobile station identification number(up to 10 digits)

42. TEMPORARY MOBILE
SUBSCRIBER IDENTITY [TMSI]
• The TMSI is used for the subscriber’s
confidentiality.
• It should be combined with the l a i to
uniquely identify AMS.
• Since the t m s i has only local significance
(that is, within the M S C/V L R area), the
structure may be chosen by each
administration.
• The T M S I should not consist of more than
four octets.

43. Mobile Station Roaming
Number[MSRN]
• HLR knows in what service area the
subscriber is located.
• In order to provide a temporary number to be
used for routing, the HLR requests the
current M S C/V L R to allocate a mobile
station roaming number(MSRN) to the called
subscriber and to return it.
• At reception of the M S R N, H L R sends it to
the MSC, which now can route the call to the
VLR where the called subscriber is currently
registered.

44. INTERNATIONAL MOBILE
EQUIPMENT IDENTITY [IMEI]
• The IMEI is used for equipment identification. An IMEI
Uniquely identifies a mobile station as a piece or
assembly of equipment.
• IMEI = TAC + FAC + SNR + SP
– T A C= type approval code (6 digits),determined by GSM body
– F A C= final assembly code (2 digits), identifies the manufacturer
– S N R= serial number (6 digits), uniquely identifying all
equipment within each TAC and FAC
– S P = spare for future use (1 digit)

45. BASE STATION SUBSYSTEM (BSS)
TWO PARTS OF BSS
• BTS
• BSC
Base Station Subsystem (BSS)
Base Transceiver Station (BTS)
Base Station Controller (BSC)
• Network Subsystem
Mobile Switching Center (MSC)
Home Location Register (HLR)
Visitor Location Register (VLR)
Authentication Center (AUC)
Equipment Identity Register (EIR)
• Authentication Center (AUC)
- mainly used for security
- data storage location and functional part of the network
- Ki is the primary element
• Equipment Identity Register (EIR)
- Database that is used to track handsets using the IMEI
(International Mobile Equipment Identity)
- Made up of three sub-classes: The White List, The Black List
and the Gray List
- Optional database

46. BASE TRANSCEIVER STATION (BTS)
The base transceiver station (BTS) is a term
used to denote a base
station in GSM terminology. A BTS consists of
an antenna and the radio equipment
necessary to communicate by radio with a
mobile station (MS). Each b t s covers a
defined area, known as a cell. A BTS is under
control of a BSC, which is in turn under control
of a MSC (mobile switching centre).

47. POWER SUPPLY TO BTS

48. BASE STATION CONTROLER (BSC)
• He base station
controller (BSC) is in
control of and supervises a
number of base
transceiver stations (BTS).
The BSC is responsible for
the allocation of radio
resources to a mobile call
and for the handovers that
are made between base
stations under his control.
Other handovers are under
control of the MSC.

49. Mobile switching centre-m s c
The mobile switching centre
(MSC)
Is a telephone exchange that
makes the connection
between mobile users within
the network from mobile
users within the network and
from mobile users to other
mobile network
The MSC also administrate
handovers to neighbouring
base station, keeps a record of
the location of the mobile
subcriber,is responsible for
subscriber service and billing

50. HOME LOCATION REGISTER(HLR)
The home location register is a database from a mobile network in
which information from all mobile subscribers is stored. The HLR
contains information about the subscribers identity, his telephone
number, the associated services and general information about the
location of the subscriber. The exact location of the
subscriber is kept in a visitor location register.
Visitor location register (VLR)The visitor location
register (VLR) is a database in a mobile communications network
associated to a mobile switching centre (MSC). The VLR contains
the exact location of all mobile subscribers currently present in the
service area of the MSC. This information is necessary to route a
call to the right base station. The database entry of the subscriber
is deleted when the subscriber leaves the service area.

51. GATEWAY MOBILE SWITCHING
CENTRE(GMSC)
• The gateway mobile
switching centre (GMSC) is a
special kind of MSC that is
used to route calls outside
the mobile network.
Whenever a call for a mobile
subscriber comes from
outside the mobile network,
or the subscriber wants to
make a call to somebody
outside the mobile network
the call is routed through the
GMSC.
• In practice, the GMSC is just a
function that can be part of
AMSC.

52. AUTHENTICATION CENTER
(AUC)
• Stores subscriber authentication data called k I, a copy
of which is also stored in in the SIM card
• Generates security related parameters to authorize a
subscriber (SRES-signed response)
• Generates unique data pattern called cipher key (KC) for
user data encryption
• Provides triplets - RAND, SRES & KC, to the HLR on
request.

53. CALL FLOW

54. MOBILE ORIGINATED CALL
54
MS
MS
BTS
BTS
BTS
BSC
BSC
MSC
VLR
GMSC
HLR
PSTN
EIR
AuC
Req for dedicated channel
for signaling (RACH)
Give SDCCH
Allocates SDCCH using the AGCH
Sends call set-up request including
dialled digits on SDCCH
Call set-up forwarded
to BSC
Call set-up forwarded
to MSC
Authentication request
(SDCCH)
Authentication response
(SDCCH)
Authentication response
(SDCCH)
Assigns TCH Req
Activate TCH
TCH assigned
Assn complete
Release SDCCH
SDCCH released
ACM
Ring tone over FACCH

Ring alert
Called Sub answers
Connect
message
Ring tone ceases over FACCH
Speech path enabled

55. NEW FEATURE OF GSM
Mobile number portability
• There has been rapid growth in the penetration of telephony services in the last few
years. But the growth has not been
• Exponential in the quality of service offered or openness of business.
• Consumers are not satisfied with the operators’ services and schemes.
• Traditionally, consumers are required to give up their mobile number on changing
service providers. As a result, they are hugely inconvenienced by having to inform
everyone about the change in their number.
• Besides there is likelihood of important calls (from people who didn’t have the new
number) being missed out, and so on.
• The picture has now changed dramatically with the introduction of mobile number
portability (MNP)

56. TYPES OF MNP
• Mobile number portability mobile number portability enables consumers to retain their mobile
numbers when changing service providers, service types and/or locations. The internet engineering
task force (I e t f) has defined three types of number portability: service provider portability, location
portability and service portability.
• Service provider portability: it enables a customer to retain his existing mobile number when
changing from one service provider to another in the same area.
• Location portability: it enables a customer to retain his existing mobile number without impairment
of quality, convenience or reliability when shifting from one geographic location to another.
• Service portability: it enables a customer to retain his existing mobile number without impairment of
quality, convenience or reliability when switching from one service technology to another service
technology—for example, from c d m a to GSM.
Mnp terminology
• Donor operator. Operator from whose network the customer is porting out.
• Recipient operator. Operator who will be providing services to the customer after porting.
• Number portability database. Collection/repository of all the ported numbers. Provides a unique
routing number in response to a query from any network operator.
• Routing number. A unique number stored in the number portability database that is used to route
the call to the recipient operator

57. DATABASE STRUCTURE
DISTRIBUTED DATABASE CENTRALISED DATABASE

58. CONCLUSION……
Basic features provided by GSM
• Call waiting
- Notification of an incoming call while on the handset
• Call hold
- Put a caller on hold to take another call
• Call barring
- All calls, outgoing calls, or incoming calls
• Call forwarding
- Calls can be sent to various numbers defined by the user
• Multi party call conferencing
- Link multiple calls together
- Advanced features provided by GSM
• Calling line id
- Incoming telephone number displayed
• Alternate line service
- One for personal calls
- One for business calls
• Closed user group
- Call by dialing last for numbers
• Advice of charge
- Tally of actual costs of phone calls
• Fax & data
- Virtual office / professional office
• Roaming
- Services and features can follow customer from market to market

59. ADVANTAGES OF GSM
• Crisper, cleaner quieter calls
• Security against fraud and eavesdropping
• International roaming capability in over 100 countries
• Improved battery life
• Efficient network design for less expensive system
expansion
• Efficient use of spectrum
• Advanced features such as short messaging and caller id
• A wide variety of handsets and accessories
• High stability mobile fax and data at up to 9600 baud
• Ease of use with over the air activation, and all account
information is held in a smart card which can be moved
from handset to handset

60. T H A N K Y O U