Gateway Interworking Mobile Switching Center Computer Science Essay

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Nowadays, SMS which defined as short messaging services is a communication technology that widely used. SMS plays an important role in many people daily lives, especially the younger generations. The users of SMS is growing rapidly from day to day, there are almost 3.5 trillion of SMS messages are exchanged in 2008 as indicated by Portio Research(2008).

SMS is available for most mobile phone and does not require to download any software for used it. A single SMS can support up to 160 characters and those characters can be in words or numbers or an alphanumeric combination.

SMS is a universal data service and is supported on GSM, TDMA, and CDMA networks. An SMS message can originate from an external system such as e-mail or mobile device and is routed through the network, via the short messaging service center (SMSC), to the destination.SMS is able to deliver messages in any time, regardless of whether phone calls is in progress.

SMS is store and forward service which means the message will pass through the SMS Center before it is delivery to the recipient and it has one or more messaging centers to manage and handle the SMS for each mobile network. Therefore SMS is reliable in delivery of the message. Even though the recipient is temporary unavailable for receiving the message due to the signal issue or the recipient mobile devices is off.

A SMS is able to send to many people at a time, and it has the features of confirmation of message delivery, which is means that the sender will received a notification message when the message is successfully delivery to the recipient.

2.0 Network Elements and Architecture

Figure 1

Short Messaging Entities (SME)

SME is an entity that may receive or send short messages. The SME may be located in a mobile station, fixed network or another service center.

Short Message Service Center (SMSC)

Short message service center (SMSC) is responsible for handling the SMS operation such as relaying and store-and forwarding of a short message between an SME and mobile station. Every SMS message that sent out from a mobile phone will reach the SMS center first before forward to the destination. The main responsibility of SMSC is to route the SMS messages and regulate the process. The SMSC will store the SMS message if the recipient is unavailable such as the mobile phone of recipient is switched off or out of signal, while the recipient is available, the SMSC will forward the SMS message to the recipient.

SMS-Gateway/Interworking Mobile Switching Center (GMSC/ IWMSC)

The SMS gateway MSC (SMS-GMSC) is an MSC capable of receiving a short message

from an SMSC, interrogating a home location register (HLR) for routing information, and

delivering the short message to the "visited" MSC of the recipient mobile station.

The SMS interworking MSC (SMS-IWMSC) is an MSC capable of receiving a short

message from the mobile network and submitting the message to the appropriate SMSC. The SMSGMSC/SMS-IWMSC is typically integrated with the SMSC.

Home Location Register (HLR)

HLR is a database that used for management and serve as permanent storage to store the subscriptions and service profiles. Upon interrogation by the SMSC, the HLR provides the routing information for the indicated subscriber. The HLR also informs the SMSC, which has previously initiated unsuccessful short message delivery attempts to a specific mobile station, that the mobile station is now recognized by the mobile network to be accessible.

Visitor Location Register (VLR)

VLR is integrated with the MSC.VLR contains of information about subscribers that currently being in the service area of the MSC in order to service visiting subscribers.

Mobile Switching Center (MSC)

MSC performs the switching functions of the system and controls calls to and from other telephone and data systems.

Base Station System (BSS)

All radio-related functions are performed in the base station system (BSS). The BSS

consists of base station controllers (BSCs) and the base transceiver stations (BTSs), and

its primary responsibility is to transmit voice and data traffic between the mobile stations.

Mobile Station (MS)

The mobile station (MS) is the wireless terminal capable of receiving and originating short messages as well as voice calls. The wireless network signaling infrastructure is based on Signaling System No 7 (SS7). SMS makes use of the mobile application part (MAP) which defines the methods and mechanisms of communication in wireless networks, and uses the services of the SS7 transaction capabilities application part (TCAP). An SMS service layer makes use of the MAP signaling capabilities and enables the transfer of short messages between the peer entities.

Common Channel Signaling System 7 (SS7)

Digital signaling control network used by network elements of wired and wireless telephone carriers to exchange control information for call setup, routing, mobility management.

Mobile-Terminated Short Message Example

Figure 2

The short message is submitted from the SME to the SMSC.

After completing its internal processing, the SMSC interrogates the HLR and receives the routing information for the mobile subscriber.

The SMSC sends the short message to the MSC using forwardShortMessage operation.

Subsequently the MSC retrieves the subscriber information from the VLR. This operation includes an authentication procedure.

The MSC transfers the short message to the MS.

The MSC returns to the SMSC the outcome of the forwardShortMessage operation.

If requested by the SME, the SMSC returns a status report indicating delivery of the short message.

Mobile-Originated Short Message Example

Figure 3

The MS transfers the short message to the MSC.

The MSC interrogates the VLR to verify that the message transfer does not violate the supplementary services invoked or the restrictions imposed.

The MSC sends the short message to the SMSC using the forwardShortMessage operation.

The SMSC delivers the short message to the SME.

The SMSC acknowledges to the MSC the successful outcome of the forwardShortMessage operation.

The MSC returns to the MS the outcome of the MO-SM operation.

3.0 Advantages and Disadvantages of SMS

There are many advantages and disadvantages of SMS, in this chapter, the author will evaluate the advantages and disadvantages of SMS.


As indicated by Xq.Meng et al(2005) one of the advantages of the SMS is there is no geographical constraints for exchanging the message with other user, which means by the user can send the message globally. In addition, most of the cellular networks can support the delivery and routing of SMS messages. Besides, the researchers also claimed that the store-and-forward communication model is similar to emails, in which the message will store in the server temporary and retransmitted later if the message cannot immediately reach the destination, rather than discarded the message.

A.Walsh(2009) also noted that the it is no geographical constraints, the users can send the SMS message wherever and whenever they please.Besides, SMS is able to send out messages to large number of people at a time, and it can integrate well with other system.

Zhang and Mao(2008), as cited by Phau and Teah(2009) claimed that SMS is usefulness, because it can be apply in many field such as personal used, commercial and education. Besides, SMS is ease of use example like the user just has to click a few buttons and type the text then send it. It does not involve of complexity procedure. In addition, the researchers said that SMS is cost effectiveness because it is much cheaper than the cost of the phone call. Furthermore, SMS is ubiquity, user can send SMS on anytime and anywhere they like.SMS is effectiveness and reliable because of the guaranteed message delivery and the message usually will delivery to the destination in a short period of time.

Goh and Liew(2008) also agreed that user can texts to other mobile phone user worldwides which mean that SMS has no geographical limitation, the users can send a message to other user that located in different countries. Besides, researchers also agreed that the SMS is cost effectiveness, because the cost of the SMS is affordable for every mobile users.

In addition, Phau and Teah(2009) also stated that SMS is ease of use because the user does not need additional advanced knowledge on how to use SMS. Carla et al(2010) also noted that the SMS is ease of use because it is easy for user to learn how to use it.

Based on the statements of above, the author can conclude that the advantages of SMS includes guaranteed message delivery, reliable, cost effectiveness , ease of use, effectiveness, global reach and ubiquity.


SMS spam is one of the disadvantages of the SMS, which is mean the user will received many unwanted commercial advertisements through the SMS (Enrique et al,2005).While S. Herman also claimed that SMS spam is a disadvantages of the SMS.Clearsms(2008) also indicated that the SMS spam will make the user feel frustrating.

A.Walsh(2009) noted that the disadvantages of SMS is the SMS massage could not be received or sent out if there is no signal or minimal signal of the mobile phone, because some of the mobile phone service provider might have limited coverage area for the signal.

Goh and Liew(2008) indicated that small and lower resolution screens that only can display few lines of texts at a time is the disadvantages of SMS. Besides, the input of text might be slow and more difficult compared to typing with a keyboard on a PC or laptop due to most mobile devices depends on numeric keypads that mapped with multiple characters for input the text.

According to the statements above, the author can noted that the disadvantages of the SMS includes SMS spam, signal depended, small and low resolution of screens for mobile phone and the input speed of text might be slower compare to input text with a keyboard on PC or Laptop.

SMS security

The privacy of the SMS content cannot be assured, because the SMS is sent as a plain text over the air which is mean by it has no data encryption for protect the content that being sent. Therefore, the contents of the SMS messages are visible to the network operator's systems and personnel. The SMS is only will be used for sending the confidential information when there are available of a solution which is satisfying of authentication, confidentiality ,integrity and non-repudiation to solve the security issues of SMS technology. Authentication is concerned with only specific users with specific combination of device, application, memory card, and SIM card that are allowed to access corporate data. This way the users or unauthorized persons cannot change any part of the combination to obtain access to sensitive data. Confidentiality is about ensuring that only the sender and intended recipient of a message can read its content. Integrity is concerned with ensuring that the content of the messages and transactions not being altered, whether accidentally or maliciously. Nonrepudiation is about providing mechanisms to guarantee that a party involved in a transaction cannot falsely claim later that he/ she did not participate in that transaction. An end-to-end key based encryption technology for SMS plugs the gaps in transit security of SMS. Authentication added for resident SMS security access together with encryption, addresses the confidentiality issue of SMS technology. Added features of message integrity and digital signing of SMS address integrity and Non Repudiation for SMS technology.

There are some SMS security threats that would affected the security and trusty of using SMS such as:

Message Disclosure

The messages might be easy to snooped and intercepted during the transmission due to there are no encryption applied for the SMS transmission by default. Moreover, SMS messages are stored as plain text as mention above by the SMSC before it successfully forward to the recipient. Therefore, the contents of SMS could be view or modified by users or operator in the SMSC who have access to the messaging system.


Many people have receiving the SMS spam while the SMS is a legitimate marketing channel for the companies to use it for the marketing purpose. In addition, the availability of bulk SMS broadcasting utilities makes it easy for virtually everyone to send out mass SMS messages.

Flooding / Denial of Service (DoS) Attacks

Flooding or DoS attacks are made possible by sending repeated messages to a target mobile phone, making the victim's mobile phone inaccessible. The SMS protocol could be exploited to launch a DoS attack on a cellular phone network. For example, it was found that sending 160 text messages a second was enough to disrupt all the cell phones.

SMS Phone Crashes

Some vulnerable mobile phones may crash if they receive a particular type of malformed short message. Once a malformed message is received, the infected phone becomes inoperable.

SMS Viruses

The potential of viruses being spread through SMS is becoming greater while the mobile phones are getting more powerful and programmable. In addition, the ability of SIM application toolkits that allows applications to access the dialling functions and phone book entries might make SMS suitable platform for spreading self-replicating virus.

4.0 Adoption of SMS advertising

SMS advertising is considered as E-marketing which is means by use of electronic communication technology to achieve the marketing objective and it is also consider as direct marketing. SMS is widely used by many companies for advertising because the mobile phone has become very common tools that widely use around the world. According to the Dickinger et al.(2004), there are about 10 billion of SMS messages sent by the mobile phone users each month and it also resulting that SMS has become the most popular mobile data service. Therefore, SMS advertising can help to advertise to widest possible audience.

Enpocket, as cited by Bamba and Barnes(2006) that SMS advertising deliver a 15 per cent response rate, which also as twice of the response rate for the direct mail or e-mail. Besides, SMS advertising are more successful at building brand awareness than the radio and TV. Phau and Teah(2009) also agreed that the SMS advertising make higher response rates than the internet banner ads and direct mail

Bamba and Barnes(2006) noted that one of the advantages of the SMS advertising is the company can send the SMS advertising to the customer or consumer without to get permission from them. Therefore, it is better than the other ways of advertising, such as phone call advertising, the consumer will usually deny or end-up the call before the staffs of the company promote their products. However, in some of the European countries, the advertisers are required to obtain the permission before they contacting to the customers especially via the e-mail or SMS due to the legislation of the country and because of sending SMS advertisements without the consent of the consumers is considered as a violation of privacy.

As indicated by Phau and Teah(2009),the advertiser use the SMS to updates the latest news about their company and keep in touch with the customers. Furthermore, some of the company's marketers send the coupon to the customer's mobile phones via SMS. For example, some company will send discount coupon for the customers who are birthday of the month to encourage the customer to use the coupon and purchase the products from the company.

Barnes, as cited by Phau and Teah(2009), the younger consumer market is easy to get attracted by SMS and the SMS is the preferred way to communicate with those younger consumer. Thus, the marketers are preferred to use SMS advertising as a marketing tool.

There are six ways of using SMS for advertising, such as special offers, promote products and services, voting, brand building and information requests.(Bamba and Barnes,2006)

However the Shintaro(2005) provided another six terms in using the SMS advertising which are Branding strategy, Facilitating conditions, Location-based services, Service costs, Regulatory control and Cultural barriers. The branding strategy is means by increase the awareness and brand recognize of customer. The facilitating is provides the basic infrastructure to enable consumers to send and receive the SMS messages.The Location-based services provides the promotional offers according to the customer based on the customer's location by using the global positioning system (GPS).Example like when the customer is reach the certain area, then the company can send SMS message to the customer about the information of the nearby restaurants. The Service costs is about to understand and choose the lower cost of SMS service provider for SMS advertising. The Regulatory control is about not violation of privacy of the customer, because it is serious concern for European legislatures. While the last term is Cultural barriers, the marketer or the advertiser have to know the culture of the target customer, and send the SMS advertisement that suit for the culture of the customer, because different countries have their own culture.

Based on the statements above, SMS advertising is a widely used in E-marketing.SMS advertising can help the company to achieve the marketing purposes such as promoting product, brand building, and maintain the relationship with the customer. Furthermore, there are several things that the advertiser or marketer have to consider when implements of SMS advertising as mentioned above.

5.0 Choosing the SMS service provider

There are several things that needed to be considered when choosing the SMS service provider such as:

The cost to send a SMS message

The monthly minimum usage requirement

The reliability of the SMS service provider

The author has chosen 3 service providers in Malaysia for the small businesses to compare the rate of SMS, which are Maxis,Digi and Celcom. The reason that the author choose these 3 service provider is because these 3 service provider are the top 3 communication service provider of Malaysia, therefore there are reliable and have the wide coverage over the Malaysia.


Figure 4

The author has decides to select the BUSINESS VALUE PLUS 50 plan from the Maxis for the comparison, because this is the lowest minimum charge per month among the plan, thus it is suitable for the small business.

The figure 4 is the rates of the Value First plan from the Maxis. According to the figure 4, The SMS charge is RM0.05 per SMS for Maxis to Maxis and RM 0.15 per SMS for Maxis to others service provider and the minimum of monthly fees is RM 50.


Figure 5

The author has decides to select the BIZ 25 plan from the Digi, because this plan is suitable for the small businesses and start ups.

The figure 5 is the rates of the BIZ plan from the Digi. According to the figure 5, the SMS charge is RM0.10 per SMS for send SMS to all network and the minimum of monthly fees is RM 25.


Figure 6

The author has decides to select the P 28 plan from the Celcom, because this plan is the lowest monthly charge rate that suitable for the small businesses.

The figure 6 is the rates for the P 28 plan from the Celcom. According to the figure 6, the SMS charge is RM0.02 per SMS for send SMS to Celcom network and RM 0.10 for SMS all network and the minimum of monthly fees is RM 28.


As a result, the author found that the celcom's plan P 28 is the lowest charge rate for the SMS, because the charge per SMS to the celcom network is just cost RM0.02 which is cheaper than the Maxis plan that cost RM 0.05 and Digi plan that cost RM 0.10. While for the SMS to other network is just cost RM 0.10 which is cheaper than the maxis SMS charge rate to other network which is RM 0.15.Therefore, the celcom's P 28 plan is the most suitable for the small businesses that newly implement the SMS in their business.

Send SMS Messages from a Computer / PC

In this chapter, the author will introduce the ways to send SMS from a computer. There are two ways of sending a SMS from a computer:

Connect a mobile phone or GSM/GPRS modem to a computer / PC. Then use the computer / PC and AT commands to instruct the mobile phone or GSM/GPRS modem to send SMS messages.

Connect the computer / PC to the SMS center (SMSC) or SMS gateway of a wireless carrier or SMS service provider. Then send SMS messages using a protocol / interface supported by the SMSC or SMS gateway.

6.1 Sending SMS Messages from a Computer Using a Mobile Phone or GSM/GPRS Modem

The SMS specification has defined a way for a computer to send SMS messages through a mobile phone or GSM/GPRS modem. A GSM/GPRS modem is a wireless modem that works with GSM/GPRS wireless networks. A wireless modem is similar to a dial-up modem. The main difference is that a wireless modem transmits data through a wireless network whereas a dial-up modem transmits data through a copper telephone line.

To send SMS messages, first place a valid SIM card from a wireless carrier into a mobile phone or GSM/GPRS modem, which is then connected to a computer. There are several ways to connect a mobile phone or GSM/GPRS modem to a computer. For example, they can be connected through a serial cable, a USB cable, a Bluetooth link or an infrared link. The actual way to use depends on the capability of the mobile phone or GSM/GPRS modem. For example, if a mobile phone does not support Bluetooth, it cannot connect to the computer through a Bluetooth link.

After connecting a mobile phone or GSM/GPRS modem to a computer, you can control the mobile phone or GSM/GPRS modem by sending instructions to it. The instructions used for controlling the mobile phone or GSM/GPRS modem are called AT commands. (AT commands are also used to control dial-up modems for wired telephone system.) Dial-up modems, mobile phones and GSM/GPRS modems support a common set of standard AT commands. In addition to this common set of standard AT commands, mobile phones and GSM/GPRS modems support an extended set of AT commands. One use of the extended AT commands is to control the sending and receiving of SMS messages.

The following table lists the AT commands that are related to the writing and sending of SMS messages:

AT command



Send message


Send message from storage


Write message to memory


Delete message


Send command


More messages to send

One way to send AT commands to a mobile phone or GSM/GPRS modem is to use a terminal program. A terminal program's function is like this: It sends the characters you typed to the mobile phone or GSM/GPRS modem. It then displays the response it receives from the mobile phone or GSM/GPRS modem on the screen. The terminal program on Microsoft Windows is called HyperTerminal.

6.2 Sending SMS Messages Using a Protocol / Interface Supported by an SMSC or SMS Gateway

After setting up an account with a wireless carrier or an SMS service provider, you can start sending SMS messages using a protocol / interface supported by the SMSC or SMS gateway. To communicate with an SMSC, an SMSC protocol is required. Most of these SMSC protocols are proprietary to the company that developed the SMSC. One widely used SMSC protocol is SMPP (Short Message Peer to Peer). It was originally a proprietary SMSC protocol created by Logica (an SMSC vendor).

The following table lists some of the SMSC protocols and the SMSC vendors who develop the protocols:

SMSC vendor

SMSC protocol

CMG (CMG and Logica have merged into LogicaCMG.)

EMI (External Machine Interface)

UCP (Universal Computer Protocol)


SMPP (Short Message Peer to Peer)


CIMD (Computer Interface to Message Distribution)

SEMA Group

OIS (Open Interface Specification)


SMS gateways of SMS service providers and wireless carriers very often support one or more of the following protocols / interfaces: HTTP, HTTPS (HTTP + SSL encryption), XML over HTTP / HTTPS, SMTP (email to SMS), FTP. Some also support the SMPP protocol, which is usually used by advanced users. SMSC protocols other than SMPP are not commonly supported.


In conclusion, SMS is a communication technology that very popular and common is used by the people nowadays. The SMS technology has bring a lot of benefit to the people such as can communicate with other people that from different places, served as a marketing tool that for the organization to use it to achieve the marketing purpose.

The organization can adopt the SMS technology into their business, especially for the small businesses company, because the SMS is reliable, cost effectiveness, global reach and ubiquity. Therefore, it can help the company to achieve the mission and goal. Besides, the company has to consider the few term as mention in the adoption of SMS advertising chapter in order to success.

In addition, the business company should consider for choose the best service provider for them to implement the SMS technology into their business, as well as the ways of implement it.