Subscriber Identity Module
Introduction
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A Subscriber Identity Module SIM is part of a removable smart card ICC Integrated Circuit Card, also known as SIM Cards, for mobile, telephony devices such as computers and mobile phones. SIM cards securely store the servicesubscriber key IMSI used to identify a subscriber. The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device.SIM cards are available in two standard sizes. The first is the size of a credit card . mm × . mm x . mm. The newer, more popular miniatureversion has a width of mm, a height of mm, and a thickness of . mm. However most SIM cards are supplied as a fullsized card with the smaller card held in place by a few plastic links and can be easily broken off to be used in a phone that uses the smaller SIM.The use of SIM cards is mandatory in GSM devices. The equivalent of a SIM in UMTS is called the Universal Subscriber Identity Module USIM, whereas the Removable User Identity Module RUIM is more popular in CDMAbased devices. Many CDMAbased standards do not include any such card, and the service is bound to a unique identifier contained in the handset itself.The Satellite phone networks Iridium, Thuraya and Inmarsats BGAN also use SIM cards. Sometimes these SIM cards work in regular GSM phones and also allow GSM customers to roam in satellite networks by using their own SIM card in a satellite phone.The SIM card introduced a new and significant business opportunity of mobile telecoms operatorcarrier business of the MVNO Mobile Virtual Network Operator which does not own or operate a cellular telecoms network, but which leases capacity from one of the network operators, and only provides a SIM card to its customers. MVNOs first appeared in Denmark, Hong Kong, Finland and the UK and today exist in over countries including most of Europe, USA and Canada, and Australia and parts of Asia and account for approximately % of all mobile phone subscribers around the world.On some networks the mobile phone is locked to its SIM card such as on the GSM networks in the USA. This tends to happen only in countries where mobile phones are heavily subsidised, but even then not all countries and not all operators such as in the UK typically most phones with subsidies are not SIMlocked. In countries where the phones are not subsidised, such as Italy and Belgium, all phones are unlocked. Where the phone is not locked to its SIM card, the users can easily switch networks by simply replacing the SIM card of one network with that of another while using only one phone. This is typical for example among young users who may want to optimise their telecoms traffic by different tariffs to different friends on different networks. It is called the SIM card switchSIM operating systems come in two main types Native and Java Card. Native SIMs are based on proprietary, vendor specific software whereas the Java Card SIMs are based on standards, particularly Java Card which is a subset of the Java programming language specifically embedded devices. Java Card allows the SIM to contain programs that are hardware independent and interoperable.
SIM cards store network specific information used to authenticate and identify subscribers on the Network, the most important of these are the ICCID, IMSI, Authentication Key Ki, Local Area Identity LAI and OperatorSpecific Emergency Number. The SIM also stores other carrier specific data such as the SMSC Short Message Service Center number, Service Provider Name SPN, Service Dialing Numbers SDN, AdviceOfCharge parameters and Value Added Service VAS applications. look to GSM .Each SIM is Internationally identified by its ICCID Integrated Circuit Card ID. ICCIDs are stored in the SIM cards and are also engraved or printed on the SIM card body during a process called personalization. The ICCID is defined by the ITUT recommendation E.. The number is up to digits long and in addition is often associated with a single check digit calculated using the Luhn algorithm.The SIM card is designed not to allow the Ki to be obtained using the smartcard interface. Instead, the SIM card provides a function, RUN GSM ALGORITHM, that allows the phone to pass data to the SIM card to be signed with the Ki. This, by design, makes usage of the SIM card mandatory unless the Ki can be extracted from the SIM card, or the carrier is willing to reveal the Ki. In practice, the GSM crypto algorithm for computing SRES_ see step , below from the Ki has certain vulnerabilities which can allow the extraction of the Ki from a SIM card and the making of a duplicate SIM card.The SIM stores network state information, which is received from the Location Area Identity LAI. Operator networks are divided into Location Areas, each having a unique LAI number. When the device changes locations, it stores the new LAI to the SIM and sends it back to the operator network with its new location. If the device is power cycled, it will take data off the SIM, and search for the previous LAI. This saves time by avoiding having to search the whole list of frequencies that the telephone normally would.Most SIM cards will orthogonally store a number of SMS messages and phonebook contacts. The contacts stored are in simple Name and number pairs entries containing multiple phone numbers and additional phone numbers will usually not be stored on the SIM card. When a user tries to copy such entries to a SIM the handsets software will break them up into multiple entries, discarding any information that isnt a phone number. The number of contacts and messages stored depends on the SIM early models would store as little as messages and contacts while modern SIM cards can usually store over contacts.In July , the Finnish government announced that a Citizen Certificate a governmentguaranteed electronic identity included in a SIM card would be made available to every individual resident in Finland before the end of , allowing mobile phone users to access eservices on the move. The Citizen Certificate has been described as basically an eID card that will be compatible with several hardware devices, such as mobile phones, PDAs, personal computers, digital TV sets, and public web kiosks. It is based on open standards and secured Public Key Infrastructure .
Card enclosure
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A card enclosure is a container for smart cards, credit cards, debit cards, telephone cards, visiting cards, business cards and other cards of similar size. Most cards have dimensions that follow the ID format of the ISO standard which specify the physical dimensions for cards to be . × . mm. The enclosures can be made of metal, leather, or plastic and come in various colors and designs. Sometimes having a laser engraved design for aesthetic purposes.A smart card, chip card, or integrated circuit card ICC, is defined as any pocketsized card with embedded integrated circuits which can process information. This implies that it can receive input which is processed by way of the ICC applications and delivered as an output. There are two broad categories of ICCs. Memory cards contain only nonvolatile memory storage components, and perhaps some specific security logic. Microprocessor cards contain volatile memory and microprocessor components. The card is made of plastic, generally PVC, but sometimes ABS. The card may embed a hologram to avoid counterfeiting. Using smartcards also is a form of strong security authentication for single signon within large companies and organizations.The automated chip card was invented by German rocket scientist Helmut Gröttrup and his colleague Jürgen Dethloff in the patent was finally approved in . The first mass use of the cards was for payment in French pay phones, starting in Télécarte.Roland Moreno actually patented his first concept of the memory card in . In , Michel Ugon from Honeywell Bull invented the first microprocessor smart card. In , Bull patented the SPOM Self Programmable Onechip Microcomputer that defines the necessary architecture to autoprogram the chip. Three years later, the very first CP based on this patent was produced by Motorola. At that time, Bull had patents related to smart cards. In , Bull sold its CP Division together all its patents to Schlumberger. Schlumberger combined its smart card department and CP and created Axalto. In , Axalto and Gemplus, at the time the worlds no. and no. smart card manufacturers, merged and became Gemalto.A smart card, combining credit card and debit card properties. The by mm security chip embedded in the card is shown enlarged in the inset. The contact pads on the card enables electronic access to the chip.A smart card, combining credit card and debit card properties. The by mm security chip embedded in the card is shown enlarged in the inset. The contact pads on the card enables electronic access to the chip.The second use was with the integration of microchips into all French debit cards Carte Bleue completed in . When paying in France with a Carte Bleue, one inserts the card into the merchants terminal, then types the PIN, before the transaction is accepted. Only very limited transactions such as paying small autoroute tolls are accepted without PIN.
Smartcardbased electronic purse systems in which value is stored on the card chip, not in an externally recorded account, so that machines accepting the card need no network connectivity were tried throughout Europe from the mids, most notably in Germany Geldkarte, Austria Quick, Belgium Proton, France Moneo, the Netherlands Chipknip and Chipper, Switzerland Cash, Norway Mondex, Sweden Cash, Finland Avant, UK Mondex, Denmark Danmønt and Portugal Portamoedas Multibanco.The major boom in smart card use came in the s, with the introduction of the smartcardbased SIM used in GSM mobile phone equipment in Europe. With the ubiquity of mobile phones in Europe, smart cards have become very common.The international payment brands MasterCard, Visa, and Europay agreed in to work together to develop the specifications for the use of smart cards in payment cards used as either a debit or a credit card. The first version of the EMV system was released in . In a stable release of the specifications was available. EMVco, the company responsible for the longterm maintenance of the system, upgraded the specification in and most recently in . The goal of EMVco, is to assure the various financial institutions and retailers that the specifications retain backward compatibility with the version.With the exception of countries such as the United States of America there has been significant progress in the deployment of EMVcompliant point of sale equipment and the issuance of debit and or credit cards adhering the EMV specifications. Typically, a countrys national payment association, in coordination with MasterCard International, Visa International, American Express and JCB, develop detailed implementation plans assuring a coordinated effort by the various stakeholders involved.The backers of EMV claim it is a paradigm shift in the way one looks at payment systems. In countries where banks do not currently offer a single card capable of supporting multiple account types, there may be merit to this statement. Though some banks in these countries are considering issuing one card that will serve as both a debit card and as a credit card, the business justification for this is still quite elusive. Within EMV a concept called Application Selection defines how the consumer selects which means of payment to employ for that purchase at the point of sale.For the banks interested in introducing smart cards the only quantifiable benefit is the ability to forecast a significant reduction in fraud, in particular counterfeit, lost and stolen. The current level of fraud a country is experiencing, coupled with whether that countrys laws assign the risk of fraud to the consumer or the bank, determines if there is a business case for the financial institutions. Some critics claim that the savings are far less than the cost of implementing EMV, and thus many believe that the USA payments industry will opt to wait out the current EMV life cycle in order to implement new, contactless technology.Smart cards with contactless interfaces are becoming increasingly popular for payment and ticketing applications such as mass transit. Visa and MasterCard have agreed to an easytoimplement version currently being deployed in the USA. Across the globe, contactless fare collection systems are being implemented to drive efficiencies in public transit. The various standards emerging are local in focus and are not compatible, though the MIFARE Standard card from Philips has a considerable market share in the US and Europe.Smart cards are also being introduced in personal identification and entitlement schemes at regional, national, and international levels. Citizen cards, drivers’ licenses, and patient card schemes are becoming more prevalent For example in Malaysia, the compulsory national ID scheme MyKad inlcudes different applications and is rolled out for million users. Contactless smart cards are being integrated into ICAO biometric passports to enhance security for international travel.
Usage in mobile phone standards
GSM Global System for Mobile communications originally from Groupe Spécial Mobile is the most popular standard for mobile phones in the world. Its promoter, the GSM Association, estimates that % of the global mobile market uses the standard. GSM is used by over billion people across more than countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signalling and speech channels are digital, and thus is considered a second generation G mobile phone system. This has also meant that data communication was easy to build into the system.The ubiquity of the GSM standard has been an advantage to both consumers who benefit from the ability to roam and switch carriers without switching phones and also to network operators who can choose equipment from any of the many vendors implementing GSM. GSM also pioneered a lowcost, to the network carrier, alternative to voice calls, the Short message service SMS, also called text messaging, which is now supported on other mobile standards as well. Another advantage is that the standard includes one worldwide Emergency telephone number, . This makes it easier for international travellers to connect to emergency services without knowing the local emergency number.wer versions of the standard were backwardcompatible with the original GSM phones. For example, Release of the standard added packet data capabilities, by means of General Packet Radio Service GPRS. Release introduced higher speed data transmission using Enhanced Data Rates for GSM Evolution EDGE..In , the European Conference of Postal and Telecommunications Administrations CEPT created the Groupe Spécial Mobile GSM to develop a standard for a mobile telephone system that could be used across Europe. In , a memorandum of understanding was signed by countries to develop a common cellular telephone system across Europe.In , GSM responsibility was transferred to the European Telecommunications Standards Institute ETSI and phase I of the GSM specifications were published in . The first GSM network was launched in by Radiolinja in Finland with joint technical infrastructure maintenance from Ericsson. By the end of , over a million subscribers were using GSM phone networks being operated by carriers across countries.GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity. GSM networks operate in four different frequency ranges. Most GSM networks operate in the MHz or MHz bands. Some countries in the Americas including Canada and the United States use the MHz and MHz bands because the and MHz frequency bands were already allocated.
The rarer and MHz frequency bands are assigned in some countries, notably Scandinavia, where these frequencies were previously used for firstgeneration systems.GSM uses – MHz to send information from the mobile station to the base station uplink and – MHz for the other direction downlink, providing RF channels channel numbers to spaced at kHz. Duplex spacing of MHz is used. In some countries the GSM band has been extended to cover a larger frequency range. This extended GSM, EGSM, uses – MHz uplink and – MHz downlink, adding channels channel numbers to and to the original GSM band. Time division multiplexing is used to allow eight fullrate or sixteen halfrate speech channels per radio frequency channel. There are eight radio timeslots giving eight burst periods grouped into what is called a TDMA frame. Half rate channels use alternate frames in the same timeslot. The channel data rate is . kbits, and the frame duration is . ms.GSM has used a variety of voice codecs to squeeze . kHz audio into between . and kbits. Originally, two codecs, named after the types of data channel they were allocated, were used, called Half Rate . kbits and Full Rate kbits. These used a system based upon linear predictive coding LPC. In addition to being efficient with bitrates, these codecs also made it easier to identify more important parts of the audio, allowing the air interface layer to prioritize and better protect these parts of the signal.GSM was further enhanced in with the Enhanced Full Rate EFR codec, a . kbits codec that uses a full rate channel. Finally, with the development of UMTS, EFR was refactored into a variablerate codec called AMRNarrowband, which is high quality and robust against interference when used on full rate channels, and less robust but still relatively high quality when used in good radio conditions on halfrate channels.There are five different cell sizes in a GSM network—macro, micro, pico, femto and umbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average roof top level. Micro cells are cells whose antenna height is under average roof top level they are typically used in urban areas. Picocells are small cells whose coverage diameter is a few dozen meters they are mainly used indoors. Femtocells are cells designed for use in residential or small business environments and connect to the service provider’s network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.Cell horizontal radius varies depending on antenna height, antenna gain and propagation conditions from a couple of hundred meters to several tens of kilometres. The longest distance the GSM specification supports in practical use is kilometres mi. There are also several implementations of the concept of an extended cell, where the cell radius could be double or even more, depending on the antenna system, the type of terrain and the timing advance.Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station, or an indoor repeater with distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when a lot of call capacity is needed indoors, for example in shopping centers or airports. However, this is not a prerequisite, since indoor coverage is also provided by inbuilding penetration of the radio signals from nearby cells.
Subscriber Identity Module
One of the key features of GSM is the Subscriber Identity Module SIM, commonly known as a SIM card. The SIM is a detachable smart card containing the users subscription information and phone book. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them this practice is known as SIM locking, and is illegal in some countries.In Australia, North America and Europe many operators lock the mobiles they sell. This is done because the price of the mobile phone is typically subsidised with revenue from subscriptions, and operators want to try to avoid subsidising competitors mobiles. A subscriber can usually contact the provider to remove the lock for a fee, utilize private services to remove the lock, or make use of ample software and websites available on the Internet to unlock the handset themselves. While most web sites offer the unlocking for a fee, some do it for free. The locking applies to the handset, identified by its International Mobile Equipment Identity IMEI number, not to the account which is identified by the SIM card.In some countries such as Belgium, Costa Rica, India, Indonesia, Pakistan, and Malaysia, all phones are sold unlocked. However, in Belgium, it is unlawful for operators there to offer any form of subsidy on the phones price. This was also the case in Finland until April , , when selling subsidized combinations of handsets and accounts became legal, though operators have to unlock phones free of charge after a certain period at most months.GSM was designed with a moderate level of security. The system was designed to authenticate the subscriber using a preshared key and challengeresponse. Communications between the subscriber and the base station can be encrypted. The development of UMTS introduces an optional USIM, that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user whereas GSM only authenticated the user to the network and not vice versa. The security model therefore offers confidentiality and authentication, but limited authorization capabilities, and no nonrepudiation. GSM uses several cryptographic algorithms for security. The A and A stream ciphers are used for ensuring overtheair voice privacy. A was developed first and is a stronger algorithm used within Europe and the United States A is weaker and used in other countries. Serious weaknesses have been found in both algorithms it is possible to break A in realtime with a ciphertextonly attack, and in February , Pico Computing, Inc revealed its ability and plans to commercialize FPGAs that allow A to be broken with a rainbow table attack . The system supports multiple algorithms so operators may replace that cipher with a stronger one.
The International Mobile Equipment Identity or IMEI pronounced aɪˈmiː is a number unique to every GSM and UMTS mobile phone as well as some satellite phones. It is usually found printed on the phone underneath the battery.The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can call his or her network provider and instruct them to ban the phone using its IMEI number. This renders the phone useless, regardless of whether the phones SIM is changed.Unlike the Electronic Serial Number or MEID of CDMA and other wireless networks, the IMEI is only used to identify the device, and has no permanent or semipermanent relation to the subscriber. Instead, the subscriber is identified by transmission of an IMSI number, which is stored on a SIM card which can in theory be transferred to any handset. However, many network and security features are enabled by knowing the current device being used by a subscriber.Many countries have acknowledged the use of the IMEI in reducing the effect of mobile phone theft. For example, in the United Kingdom under the Mobile Telephones Reprogramming Act, changing the IMEI of a phone, or possessing equipment that can change it, is considered an offence under some circumstances.There is a misunderstanding amongst some regulators that the existence of a formally allocated IMEI number range to a GSM terminal implies that the terminal is approved or complies with regulatory requirements. This is not the case. The linkage between regulatory approval and IMEI allocation was removed in April with the introduction of the European R&TTE Directive. Since that date, IMEIs have been allocated by BABT acting on behalf of the GSM Association to legitimate GSM terminal manufacturers without the need to provide evidence of approval.Other countries use different approaches when dealing with phone theft. For example, mobile operators in Singapore are not required by the regulator to implement phone blocking or tracing systems, IMEIbased or other. The regulator has expressed its doubts on the real effectiveness of this kind of systems in the context of the mobile market in Singapore. Instead, mobile operators are encouraged to take measures such as the immediate suspension of service and the replacement of SIM cards in case of loss or theft.The Check Digit is calculated according to Luhn formula ISOIEC . See GSM . GPP .. The Check Digit shall not be transmitted to the network. The Check Digit is a function of all other digits in the IMEI. The Software Version Number SVN of a mobile is not included in the calculation. The purpose of the Check Digit is to help guard against the possibility of incorrect entries to the CEIR and EIR equipment. The presentation of Check Digit CD both electronically and in printed form on the label and packaging is very important. Logistics using barcode reader and EIRCEIR administration cannot use the CD unless it is printed outside of the packaging, and on the ME IMEIType Accreditation label. The check digit shall always be transmitted to the network as .
Operating systems
Java is a programming language originally developed by Sun Microsystems and released in as a core component of Sun Microsystems Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer lowlevel facilities. Java applications are typically compiled to bytecode that can run on any Java virtual machine JVM regardless of computer architecture.The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from . As of May , in compliance with the specifications of the Java Community Process, Sun made available most of their Java technologies as free software under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java and GNU Classpath.The Java language was created by James Gosling in June for use in one of his many settop box projects. The language was initially called Oak, after an oak tree that stood outside Goslings office—and also went by the name Green—and ended up later being renamed to Java, from a list of random words. Goslings goals were to implement a virtual machine and a language that had a familiar CC++ style of notation. The first public implementation was Java . in . It promised Write Once, Run Anywhere WORA, providing nocost runtimes on popular platforms. It was fairly secure and its security was configurable, allowing network and file access to be restricted. Major web browsers soon incorporated the ability to run secure Java applets within web pages. Java quickly became popular. With the advent of Java , new versions had multiple configurations built for different types of platforms. For example, JEE was for enterprise applications and the greatly stripped down version JME was for mobile applications. JSE was the designation for the Standard Edition. In , for marketing purposes, new J versions were renamed Java EE, Java ME, and Java SE, respectively.In , Sun Microsystems approached the ISOIEC JTC standards body and later the Ecma International to formalize Java, but it soon withdrew from the process. Java remains a de facto standard that is controlled through the Java Community Process. At one time, Sun made most of its Java implementations available without charge although they were proprietary software. Suns revenue from Java was generated by the selling of licenses for specialized products such as the Java Enterprise System. Sun distinguishes between its Software Development Kit SDK and Runtime Environment JRE that is a subset of the SDK, the primary distinction being that in the JRE, the compiler, utility programs, and many necessary header files are not present.This is achieved by most Java compilers by compiling the Java language code halfway to Java bytecode – simplified machine instructions specific to the Java platform. The code is then run on a virtual machine VM, a program written in native code on the host hardware that interprets and executes generic Java bytecode. In some JVM versions, bytecode can also be compiled to native code, either before or during program execution, resulting in faster execution. Further, standardized libraries are provided to allow access to features of the host machines such as graphics, threading and networking in unified ways. Note that, although there is an explicit compiling stage, at some point, the Java bytecode is interpreted or converted to native machine code by the JIT compiler.
One of the ideas behind Javas automatic memory management model is that programmers be spared the burden of having to perform manual memory management. In some languages the programmer allocates memory for the creation of objects stored on the heap and the responsibility of later deallocating that memory also resides with the programmer. If the programmer forgets to deallocate memory or writes code that fails to do so, a memory leak occurs and the program can consume an arbitrarily large amount of memory. Additionally, if the program attempts to deallocate the region of memory more than once, the result is undefined and the program may become unstable and may crash. Finally, in non garbage collected environments, there is a certain degree of overhead and complexity of usercode to track and finalize allocations. Often developers may box themselves into certain designs to provide reasonable assurances that memory leaks will not occur.In Java, this potential problem is avoided by automatic garbage collection. The programmer determines when objects are created, and the Java runtime is responsible for managing the objects lifecycle. The program or other objects can reference an object by holding a reference to it which, from a lowlevel point of view, is its address on the heap. When no references to an object remain, the unreachable object is eligible for release by the Java garbage collector it may be freed automatically by the garbage collector at any time. Memory leaks may still occur if a programmers code holds a reference to an object that is no longer needed—in other words, they can still occur but at higher conceptual levels.The use of garbage collection in a language can also affect programming paradigms. If, for example, the developer assumes that the cost of memory allocationrecollection is low, they may choose to more freely construct objects instead of preinitializing, holding and reusing them. With the small cost of potential performance penalties innerloop construction of largecomplex objects, this facilitates threadisolation no need to synchronize as different threads work on different object instances and datahiding. The use of transient immutable valueobjects minimizes sideeffect programming.Comparing Java and C++, it is possible in C++ to implement similar functionality for example, a memory management model for specific classes can be designed in C++ to improve speed and lower memory fragmentation considerably, with the possible cost of adding comparable runtime overhead to that of Javas garbage collector, and of added development time and application complexity if one favors manual implementation over using an existing thirdparty library. In Java, garbage collection is builtin and virtually invisible to the developer. That is, developers may have no notion of when garbage collection will take place as it may not necessarily correlate with any actions being explicitly performed by the code they write. Depending on intended application, this can be beneficial or disadvantageous the programmer is freed from performing lowlevel tasks, but at the same time loses the option of writing lower level code. Additionally, the garbage collection capability demands some attention to tuning the JVM, as large heaps will cause apparently random stalls in performance.Java does not support pointer arithmetic as is supported in, for example, C++. This is because the garbage collector may relocate referenced objects, invalidating such pointers. Another reason that Java forbids this is that type safety and security can no longer be guaranteed if arbitrary manipulation of pointers is allowed.
SMS messages and contacts
Most SIM cards will orthogonally store a number of SMS messages and phonebook contacts. The contacts stored are in simple Name and number pairs entries containing multiple phone numbers and additional phone numbers will usually not be stored on the SIM card. When a user tries to copy such entries to a SIM the handsets software will break them up into multiple entries, discarding any information that isnt a phone number. The number of contacts and messages stored depends on the SIM early models would store as little as messages and contacts while modern SIM cards can usually store over contacts.SIM cloning consists of duplicating the GSM SIM card, which allows calls or other services to use the identification of the cloned SIM and to be charged to that account.In the early s, due to poor security, cloning was more common than it is today. Cloning has now been rendered more challenging technically since physical access to the SIM card is now required, contrary to simply being within radio reach.SIM cloning is now more difficult to perform, because merely duplicating the contents of the SIM does not enable a duplicate SIM to operate, since the SIM itself performs security operations on the data contained inside to avoid such copying. In order to function, the cloned SIM needs to perform security operations on the data contained, just like the original one.SIM cloning is a great concern to securitypolice services since it renders GSM locationbased service LBS unreliable when more than one handset uses the same SIM.In the movie The Bourne Supremacy, the main character clones a SIM card to enable him to listen in to calls to a U.S. official from the CIA. It is widely held that actually cloning a SIM could not be accomplished as quickly as it was in the film.A realistic time for extracting the Ki from a SIM card is approximately hours. There is % probability of damaging the card in the process. Additionally, the attacker must have preknowledge of the SIM cards PIN CHV.citation neededCracking Ki by overhearing radio GSM traffic is difficult but not impossible although highly illegal in the United States. In many countries GSM traffic is not encrypted thus with proper equipment a computer based radio scanner eg. USRP and the proper software, a hacker could overhear GSM traffic and clone SIMs.The security has been improved with the newer generation of SIM cards to be used with GSM networks, known as USIMs. The new specification implements a new publicly announced algorithm the KASUMI algorithm.SIM cloning is also sometimes used to unlock phones from foreign providers for use on your home network by using your Ki and switching between your IMSI and the IMSI that the phone expects the phone can be fooled into thinking that it has the SIM from its native provider this is commonly done for Japanese phones as well as the iPhone before its software unlock was released.
UMTS, using WCDMA, supports up to . Mbits data transfer rates in theory with HSDPA, although at the moment users in deployed networks can expect a transfer rate of up to kbits for R handsets, and . Mbits for HSDPA handsets in the downlink connection. This is still much greater than the . kbits of a single GSM errorcorrected circuit switched data channel or multiple . kbits channels in HSCSD . kbits for CDMAOne, and—in competition to other network technologies such as CDMA, PHS or WLAN—offers access to the World Wide Web and other data services on mobile devices.Precursors to G are G mobile telephony systems, such as GSM, IS, PDC, PHS and other G technologies deployed in different countries. In the case of GSM, there is an evolution path from G, to GPRS, also known as .G. GPRS supports a much better data rate up to a theoretical maximum of . kbits, though typical rates are closer to kbits and is packet switched rather than connection orientated circuit switched. It is deployed in many places where GSM is used. EGPRS, or EDGE, is a further evolution of GPRS and is based on more modern coding schemes. With EDGE the actual packet data rates can reach around kbits effective. EDGE systems are often referred as .G Systems.Since , UMTS networks in many countries have been or are in the process of being upgraded with High Speed Downlink Packet Access HSDPA, sometimes known as .G. Currently, HSDPA enables downlink transfer speeds of up to . Mbits. Work is also progressing on improving the uplink transfer speed with the HighSpeed Uplink Packet Access HSUPA. Longer term, the GPP Long Term Evolution project plans to move UMTS to G speeds of Mbits down and Mbits up, using a next generation air interface technology based upon Orthogonal frequencydivision multiplexing.The first national consumer UMTS networks launched in with a heavy emphasis on telcoprovided mobile applications such as mobile TV and video calling. The high data speeds of UMTS are now most often utilised for Internet access experience in Japan and elsewhere has shown that user demand for video calls is not high, and telcoprovided audiovideo content has declined in popularity in favour of highspeed access to the World Wide Web either directly on a handset or connected to a computer via WiFi, Bluetooth, Infrared or USB.UMTS over WCDMA uses a pair of MHz channels. In contrast, the competing CDMA system uses one or more arbitrary . MHz channels for each direction of communication. UMTS and other WCDMA systems are widely criticized for their large spectrum usage, which has delayed deployment in countries that acted relatively slowly in allocating new frequencies specifically for G services such as the United States.The specific frequency bands originally defined by the UMTS standard are – MHz for the mobiletobase uplink and – MHz for the basetomobile downlink. In the US, – MHz and – MHz will be used instead, as the MHz band was already utilized. While UMTS is the most widelydeployed UMTS band, some countries UMTS operators use the MHz andor MHz bands independently, meaning uplink and downlink are within the same band, notably in the US by AT&T Mobility, and in Australia by Telstra MHz only.
SIM digits
In telecommunication, telephony pronounced təˈlɛfəni or tehLEHfuhnee encompasses the general use of equipment to provide voice communication over distances, specifically by connecting telephones to each other.Telephones originally were connected directly together in pairs. Each user had separate telephones wired to the various places he might wish to reach. This became inconvenient when people wanted to talk to many other telephones, so the telephone exchange was invented. Each telephone could then be connected to other local ones, thus inventing the local loop and the telephone call. Soon, nearby exchanges were connected together by trunk lines, and eventually far away ones were.In modern times, most telephones are plugged into telephone jacks. Each jack is connected by inside wiring to a drop wire and then to a cable with other wires. Cables usually bring a large number of wires from all over a district access network to one wire center or telephone exchange. When the user of a telephone wants to make a telephone call, equipment at the exchange examines the dialed telephone number and connects that telephone line to another in the same wire center, or to a trunk to a distant exchange. Most of the exchanges in the world are connected to each other, forming the Public Switched Telephone Network or PSTN. By the end of the th century almost all were Stored Program Control exchanges.Digital telephony is the use of digital technology in the provision of telephone services and systems. Almost all telephone calls are provided this way, but sometimes the term is restricted to cases in which the last mile is digital, or where the conversion between digital and analog signals takes place inside the telephone. Telephony was digitized to cut the cost and improve the quality of voice services, but digital telephony was then found useful for new network services ISDN to transfer data speedily over telephone lines.IP Telephony is a modern form of telephony which uses the TCPIP protocol popularized by the internet to transmit digitized voice data. Contrast this with the operation of POTS an acronym for Plain Old Telephone Service.Computer Telephony Integration CTI enables computers to know about and control phone functions such as making and receiving voice, fax, and data calls with telephone directory services and caller identification. The integration of telephone software and computer systems is a major development in the evolution of the automated office.CTI is not a new concept. Such links have been used in the past in large telephone networks but only dedicated call centers could justify the costs of the required equipment installation. Primary telephone service providers are offering information services such as Automatic Number Identification and Dialed Number Identification Service on a scale wide enough for its implementation to bring real value to business or residential telephone usage. A new generation of applications middleware is being developed as a result of standardization and availability of low cost computer telephony links.
Network Switching Subsystem, or NSS, is the component of a GSM system that carries out switching functions and manages the communications between mobile phones and the Public Switched Telephone Network. It is owned and deployed by mobile phone operators and allows mobile phones to communicate with each other and telephones in the wider telecommunications network. The architecture closely resembles a telephone exchange, but there are additional functions which are needed because the phones are not fixed in one location. Each of these functions handle different aspects of mobility management and are described in more detail below.The Network Switching Subsystem, also referred to as the GSM core network, usually refers to the circuitswitched core network, used for traditional GSM services such as voice calls, SMS, and Circuit Switched Data calls.There is also an overlay architecture on the GSM core network to provide packetswitched data services and is known as the GPRS core network. This allows mobile phones to have access to services such as WAP, MMS, and Internet access.The Mobile Switching Center or MSC is the primary service delivery node for GSM, responsible for handling voice calls and SMS as well as other services such as conference calls, FAX and circuit switched data. The MSC sets up and releases the endtoend connection, handles mobility and handover requirements during the call and takes care of charging and real time prepaid account monitoring.In the GSM mobile phone system, in contrast with earlier analogue services, fax and data information is sent directly digitally encoded to the MSC. Only at the MSC is this recoded into an analogue signal although actually this will almost certainly mean sound encoded digitally as PCM signal in a kbits timeslot, known as a DS in America.There are various different names for MSCs in different contexts which reflects their complex role in the network, all of these terms though could refer to the same MSC, but doing different things at different times.A Gateway MSC is the MSC that determines which visited MSC the subscriber who is being called is currently located. It also interfaces with the Public Switched Telephone Network. All mobile to mobile calls and PSTN to mobile calls are routed through a GMSC. The term is only valid in the context of one call since any MSC may provide both the gateway function and the Visited MSC function, however, some manufacturers design dedicated high capacity MSCs which do not have any BSSes connected to them. These MSCs will then be the Gateway MSC for many of the calls they handle.The Authentication Centre or AUC is a function to authenticate each SIM card that attempts to connect to the GSM core network typically when the phone is powered on. Once the authentication is successful, the HLR is allowed to manage the SIM and services described above. An encryption key is also generated that is subsequently used to encrypt all wireless communications voice, SMS, etc. between the mobile phone and the GSM core network.If the authentication fails, then no services are possible from that particular combination of SIM card and mobile phone operator attempted. There is an additional form of identification check performed on the serial number of the mobile phone described in the EIR section below, but this is not relevant to the AUC processing.Proper implementation of security in and around the AUC is a key part of an operators strategy to avoid SIM cloning.The AUC does not engage directly in the authentication process, but instead generates data known as triplets for the MSC to use during the procedure. The security of the process depends upon a shared secret between the AUC and the SIM called the Ki. The Ki is securely burned into the SIM during manufacture and is also securely replicated onto the AUC. This Ki is never transmitted between the AUC and SIM, but is combined with the IMSI to produce a challengeresponse for identification purposes and an encryption key called Kc for use in over the air communications.
