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VoIP in Mobile communication

Prepared

By

Asifuzzaman

ID: 061 846 556 Course: ETE605

Sec-2

Prepared For Dr. Mashiur Rahman Assistant Professor

Department of Electronics & Tele Communication North South University

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1. Introduction: Nowadays VoIP (Voice Over Internet Protocol) is one of the hot topics in our country

and it is also a new technology in our country. VoIP is the name of a new

communications technology that changes the meaning of the phrase telephone call. VoIP

stands for voice over Internet protocol, and it means “voice transmitted over a computer

network.”

Internet protocol (IP) networking is supported by all sorts of networks: corporate, private,

public, cable, and even wireless networks. Don’t be fooled by the “Internet” part of the

acronym. VoIP runs over any type of network. Currently, in the corporate sector, the

private dedicated network option is the preferred type. For the telecommuter or home

user, the hands-down favorite is broadband.

With VoIP, one can literally pick up his things and move to another location, within

office building or around the world, without having to forward calls to a new telephone.

VoIP’s entirely portable!

One can access the Web from your IP phone, enabling you to get important (or not so

important) announcements and e-mail on the go. It’s like having a pocket PC and a cell

phone rolled into one, specifically designed for your network.

VoIP is a win-win for everyone. The added flexibility and quicker response times

translate into greater customer satisfaction and increased productivity throughout the

organization.

In this report I want to explore how VoIP and mobile are related to each other , VoIP

subscriber growth trends and is it possible VoIP migrate to mobile carriers?

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2. How VoIP works:

Before we discover How Does VoIP Work let me give you a quick non-technical

definition of VoIP. Firstly we need a quick idea of how phones work now, so we can

compare. Our ordinary phone which is analog uses circuit switching to transport calls.

This means that a large two-way connection is opened between phones for the entire

duration of the phone call. During the conversation thousands of miles of switching

equipment and copper have to be maintained. This causes a very long chain of devices

between the two parties and can result in many problems - low voltage, poor electrical

connections, older equipment etc.

VoIP uses packet switching, which basically means that instead of an open line it only

sends information when there is something to send. It breaks the voice into tiny portions -

each packet being a separate item. Each package is sent via a one way connection in the

correct order and addressed to the same recipient. The packages pass through the internet

routing system and servers in all directions. Each package will be given the least

congested route to travel.

The end result of all this is clearer, less echo and more efficient calls. It also means that

computer can be surfing the net, downloading files, receiving email and receive a call at

the same time.

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3. Mobile Communication

GSM (Global System for Mobile communication) is a digital mobile telephony system

that is widely used in Europe and other parts of the world. GSM uses a variation of time

division multiple access (TDMA) and is the most widely used of the three digital wireless

telephony technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data,

then sends it down a channel with two other streams of user data, each in its own time

slot. It operates at either the 900 MHz or 1800 MHz frequency band.

Mobile services based on GSM technology were first launched in Finland in 1991.

Today, more than 690 mobile networks provide GSM services across 213 countries and

GSM represents 82.4% of all global mobile connections. According to GSM World, there

are now more than 2 billion GSM mobile phone users worldwide. GSM World references

China as "the largest single GSM market, with more than 370 million users, followed by

Russia with 145 million, India with 83 million and the USA with 78 million users."

Since many GSM network operators have roaming agreements with foreign operators,

users can often continue to use their mobile phones when they travel to other countries.

SIM cards (Subscriber Identity Module) holding home network access configurations

may be switched to those will metered local access, significantly reducing roaming costs

while experiencing no reductions in service.

Bearer Services a unique feature of GSM compared to older analog systems is the Short

Message Service (SMS). SMS is a bidirectional service for sending short alphanumeric

messages (up to 160 bytes) in a store-and-forward manner. For point-to-point SMS, a

message can be sent to another subscriber to the service, and an acknowledgment of

receipt is provided to the sender. SMS also can be used in cell broadcast mode for

sending messages such as traffic updates or news updates. Messages can be stored in a

smart card called the "Subscriber Identity Module" (SIM) for later retrieval. Since GSM

is based on digital technology, it allows synchronous and asynchronous data to be

transported as a bearer service to or from an Integrated Services Digital Network (ISDN)

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terminal. The data rates supported by GSM are 300, 600, 1200, 2400, and 9600 bps. Data

can use either the transparent service, which has a fixed delay but no guarantee of data

integrity, or a nontransparent service, which guarantees data integrity through an

automatic repeat request (ARQ) mechanism but with variable delay. GSM has much

more potential in terms of supporting data. The GSM standard for high-speed circuit-

switched data (HSCSD) enables mobile phones to support data rates of up to 38.4 kbps,

compared with 9.6 kbps for regular GSM networks. Transmission speeds of up to 171.2

kbps are available with mobile phones that support the GSM standard for Global System

for Mobile communication.

General Packet Radio Service (GPRS). The high bandwidth is achieved by using eight

timeslots, or voice channels, simultaneously. GPRS facilitates several new applications,

such as Web browsing over the Internet.

The Mobile Station: The mobile station (MS) consists of the radio transceiver, display

and digital signal processors, and the SIM. The SIM provides personal mobility so that

the subscriber can have access to all services regardless of the terminal's location or the

specific terminal used. By removing the SIM from one GSM cellular phone and inserting

it into another GSM cellular phone, the user is able to receive calls at that phone, make

calls from that phone, or receive other subscribed services. The SIM card may be

protected against unauthorized use by a password or personal identification number

(PIN).

Base Station Subsystem: The base station subsystem consists of two parts: the base

transceiver station (BTS) and the base station controller (BSC). These communicate

across the A-bis interface, enabling operation between components made by different

suppliers. The base transceiver station contains the radio transceivers that define a cell

and handles the radio link protocols with the mobile stations. In a large urban area, there

typically will be a number of BTSs to support a large subscriber base of mobile service

users. The base station controller provides the connection between the mobile stations

and the mobile service switching center (MSC). It manages the radio resources for the

BTSs, handling such functions as radio channel setup, frequency hopping, and handoffs.

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The BSC also translates the 13-kbps voice channel used over the radio link to the

standard 64-kbps channel used by the land-based Public Switched Telephone Network

(PSTN) or ISDN.

Mobile Services Switching Center: The mobile services switching center (MSC) acts like

an ordinary switching node on the PSTN or ISDN and provides all the functionality

needed to handle a mobile subscriber, such as registration, authentication, location

updating, handoffs, and call routing to a roaming subscriber. These services are provided

in conjunction with several other components, which together form the network

subsystem. The MSC provides the connection to the public network (PSTN or ISDN) and

signaling between various network elements that use Signaling System 7 (SS7). The

MSC contains no information about particular mobile stations. This information is stored

in two location registers that are essentially databases. The Home Location Register

(HLR) and Visitor Location Register (VLR), together with the MSC, provide the call

routing and roaming (national and international) capabilities of GSM. The HLR contains

administrative information for each subscriber registered in the corresponding GSM

network, along with the current location of the mobile device. The current location of the

mobile device is in the form of a Mobile Station Roaming Number (MSRN), which is a

regular ISDN number used to route a call to the MSC where the mobile device is

currently located. Only one HLR is needed per GSM network, although it may be

implemented as a distributed database. The Visitor Location Register (VLR) contains

selected administrative information from the HLR that is necessary for call control and

provision of the subscribed services for each mobile device currently located in the

geographic area controlled by the VLR. There are two other registers that are used for

authentication and security purposes. The Equipment Identity Register (EIR) is a

database that contains a list of all valid mobile equipment on the network, where each

mobile station is identified by its IMEI. An IMEI is marked as invalid if it has been

reported stolen or is not type approved. The authentication center is a protected database

that stores a copy of the secret key stored in each subscriber's SIM card,which is used for

authentication.

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Authentication and security since radio signals can be accessed by virtually anyone.

Authentication of users to prove their identity is a very important feature of a mobile

network. Authentication involves two functional entities, the SIM card in the mobile unit

and the authentication center (AC). Each subscriber is given a secret key, one copy of

which is stored in the SIM card and the other in the AC. During authentication, the AC

generates a random number that it sends to the mobile unit. Both the mobile unit and the

AC then use the random number, in conjunction with the subscriber's secret key and an

encryption algorithm called A3, to generate a number that is sent back to the AC. If the

number sent by the mobile unit is the same as the one calculated by the AC, the

subscriber is authenticated. The calculated number is also used, together with a TDMA

frame number and another encryption algorithm called A5, to encrypt the data sent over

the radio link, preventing others from listening in. Encryption provides an added measure

of security, since the signal is already coded, interleaved, and transmitted in a TDMA

manner , thus providing protection from all but the most technically astute eavesdroppers.

Another level of security is performed on the mobile equipment, as opposed to the mobile

subscriber. As noted, a unique IMEI number is used to identify each GSM terminal. A list

of IMEIs in the network is stored in the EIR. The status returned in response to an IMEI

query to the EIR is one of the following:

.

Authentication of users to prove their identity is a very important feature of a mobile

network. Authentication involves two functional entities, the SIM card in the mobile unit

and the authentication center (AC). Each subscriber is given a secret key, one copy of

which is stored in the SIM card and the other in the AC. During authentication, the AC

generates a random number that it sends to the mobile unit. Both the mobile unit and the

AC then use the random number, in conjunction with the subscriber's secret key and an

encryption algorithm called A3, to generate a number that is sent back to the AC. If the

number sent by the mobile unit is the same as the one calculated by the AC, the

subscriber is authenticated. The calculated number is also used, together with a

TDMAframe number and another encryption algorithm called A5, to encrypt the data

sent over the radio link, preventing others from listening in. Encryption provides an

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added measure of security, since the signal is already coded, interleaved, and transmitted

in a TDMAmanner , thus providing protection from all but the most technically astute

eavesdroppers. Another level of security is performed on the mobile equipment, as

opposed to the mobile subscriber. As noted, a unique IMEI number is used to identify

each GSM terminal. Alist of IMEIs in the network is stored in the EIR. The status

returned in response to an IMEI query to the EIR is one of the following:

White listed. Indicates that the terminal is allowed to connect to the network.

Gray listed. Indicates that the terminal is under observation from the network for possible

problems.

Black listed. Indicates that the terminal either has been reported as stolen or is not type

approved (i.e., not the correct type of terminal for a GSM network). Such terminals are

not allowed to connect to the network.

4. VoIP Wireless Phones

Several types of wireless phones are available. The first type are IP wireless phones,

which have a limited range and are strictly tied to corporate networks. For example, a

hospital or a large construction site may have wireless networking and VoIP available

over that network. VoIP wireless phones hook into the network and do VoIP within their

specified range. Features on these types of phones are generally limited.

One thing to watch for in IP wireless phones is whether they are WiSIP compatible.If

they are, the phones can include quite a few features not normally available, such as the

ability to connect to WiFi networks and IP-PBXs without the no-peak or off-peak minute

charges. These types of phones cost a bit more, but they make calling other WiSIP

phones very easy.

Finally, it can be argued that a pocket PC with VoIP capability is, indeed, a wireless

phone. These types of computers do everything that a cell phone can do. If the pocket PC

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has built-in WiFi capability, you can use it to make VoIP calls in addition to regular cell

calls.

5. Will VoIP migrate to mobile carriers?

Mobile VoIP has undoable become one of the hottest topics in the communication field.

It has also become one of the misunderstood. While the use of VoIP back in cellular

networks is nothing new for voice traffic to be defined as mobile VoIP, a mobile

originated or a mobile terminated call must originate or terminate using exclusively the

wireless carrier IP data network.

VoIP operators choose to peruse mobile VoIP themselves or will they be force to

complete with the third parties who offer disruptive services on their networks? We

belive the answer is neither. The proliferation of Mobile VoIP is unlikely because:

• Wireless carries can and will block assess fees for any third-party service that is transmitted on their network.

• End to end VoIP does not present any completing technological advantage for wireless carriers to implement themselves,

Wireless carriers have full control on their networks:

Wireless carriers own and control all network elements from handsets to switching to

spectrum to towers. Wireless carries have paid billions of dallers worldwide for

lisence.This means that on other carrier provider can use the spectrum.

Furthermore, consider the three main reasons why VoIP has made inroads in fixed telephony market.

• VoIP as a transmission medium is more different than POTS • Band width is abundant in the wired world. • Broadband service providers cannot control what travels on their networks.

None of these driving forces are present in the mobile telephony world:

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• VoIP is less efficient than the leading digital wireless communication technologies- mainly GSM and CDMA.

• Bandwidth is very scare and mobile phones are primarily used to make voice calls.

• Wireless carries have full control of their networks within regulatory body forcing operators to open access to other service provider.

The scarcity of wireless frequencies and limited capacity of cellular networks has favored

the development and deployment of technologies that make the best use of the scant

resources.The current dominant wireless technologies GSM and CDMA are clearly

superior to VoIP for voice transmission. Currently there are two billion mobile

subscribers in the world making mobile communication the largest prevailing method of

making phone calls today. With no economic or technological benefits for VoIP to

migrate to mobile networks, all the hope, hype and anticipation associated with such

migration will mostly remain unfulfilled.

6. VoIP subscriber growth enters the US mainstream:

• More telephone services are being offered over the Internet through VoIP (Voice

Over Internet protocol) and its steady growth this year will see a spillover into

mainstream US residential households and businesses by 2006, according to a

new eMarketer report.

Currently, the number of US VoIP subscribers is small, with varying estimates

predicting between 2.8 million and 6.7 million residential VoIP lines in use by the

end of 2005. In five years' time, even the most optimistic forecast predicts just

27.0 million residential VoIP subscribers, accounting for 19.6% of the 137.4

million US consumer and small business wireline subscribers at the end of 2003.

"There is still a long road ahead for consumer and business migration to VoIP,"

says Steve Butler, eMarketer Senior Analyst and author of the report. "But it is on

the verge of moving out of the early adoption phase and into the mainstream. The

next two years will mark the turning point when widespread VoIP use finally

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begins to take off."

eMarketer's new report, VoIP: Spending and Trends, released today, examines the

rapidly developing IP telephony market and the impact its growth will have on

businesses, consumers and the entire communications industry.

As of late last year, several leading VoIP service providers were beginning to see

strong VoIP subscription growth. And a wave of new forecasts for the residential

VoIP market indicates similar growth. Telecom consultancy Atlantic-ACM

estimates that US retail VoIP services revenues will increase by a compound

annual growth rate of 64% between 2003 and 2009, reaching $20.4 billion in five

years' time. Gartner Group predicts that consumer VoIP services spending will

jump from $1.9 billion in 2005 to $9.5 billion in 2008.

Butler notes that the explosive growth of broadband Internet access in US

households is driving the adoption of higher US residential VoIP usage.

eMarketer estimates that 42.3 million homes, or 36.2% of US households, will be

using broadband by the end of this year.

7.Conclusion:

GSM is the most commonly used wireless technology in the world with over 78% market

share, followed by CDMA. On the other hand VoIP is far less efficient when compared to

GSM and CDMA technologies. Considering the above situation we can say that VoIP can

play an important role in our communication technology in near future.

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References:

• VoIP for Dummies • MTI MicroFuel Cells Announces Collaboration With Korean Partner • Cell Phones - Spain's competition authority probes mobile fee increase • Abandoned SunRocket Customers Find Risk-Free Accommodation at OneSuite • 'Pistachio Heart Health Recipes' Yield Enjoyment and Health Benefits, St... • Leading Irish VoIP Provider Chooses Wowza Media Server Pro to Power

Aggressive Expansion of Streamin • Free International Mobile Calling • iPhone Repair Kits Available • Brekeke Software Confirmed OnDO PBXs Interoperability with VoIP USER • You have a book. The entire world has an iPhone. Lulu.com has the Answer. • 370 Free to Air Sat TV channels in the Arab World.

• http://en.wikipedia.org/wiki/VoIP

• http://www.fcc.gov/voip/

• http://www.voip.com/