SIM - card is mandatory and integral part of any cell phone works in standard GSM. Telephones many other standards completely do without them. Why so?
In order for the mobile phone could be served in a - a cellular network, it must be for it to "their" with a unique "name", for which the network will recognize it and refer to it. "Their" network phone becomes after registering his "name" in the subscriber base of the system.
Beginning with the earliest cellular systems, "name" phone usually had unique serial numbers of vehicles and their electronic counterparts - Electronic Serial Number (ESN).
It is this mobile phone number automatically and informs the network when accessing it to make the call.
Similarly, a call to the phone from the network passed on its ESN. Here - and then having childish problems.
Everything was very easy, when, for example, Ericsson created the first cellular network standard NMT - 450. For her, it supplied all the equipment from the network switch to mobile phones. Their rooms are, of course, have been known to produce. So all operations on "registration" on the network can be performed even at the factory. But then the number of cellular equipment manufacturers began to grow, and they used their own alpha - numeric designation serial number of vehicles. This eliminates any possibility of inconsistency simple and consistent record in the database. For "registration" phone it always had to be brought to the mobile operators. But this does not exclude the need to direct "contact" with the phone network equipment at his residence permit. Thus, at any change of telephone subscribers necessarily have to go with him in the service department of the cellular company.
First task is to solve this problem was faced by developers only have to create a new pan-European digital then cellular standards - GSM.
And they were invited to share the functions of identification equipment and subscribers.
For identification of GSM - phone used 15 - digit number unique International Mobile Equipment Identity (IMEI), assigned to each unit in the manufacture and tell them your network at the beginning of the exchange. He has also written on the package and on the phone itself - under the battery. The parameters of the called party were made in a special plug-in module - Subscriber Identity Module (SIM), inserted in the phone.
For design standard GSM, IMEI code equipment is used only for testing "legality" of telephones - cellular network fails in service "illegal" (ie, stolen) devices whose numbers appear in a special "stop list". Since the exchange of numbers all "suspicious" phones can be made directly between the cellular networks, the authorization for service of legal phone no need for any - any of their registration in the network, and the subscriber can change phones at their discretion. In addition, it should be noted that the examination itself and the IMEI code in GSM is optional and is not supported by all companies. As a result of this circumstance in the world and there is an underground market trade in stolen phones GSM.
Regarding SIM - cards, they contain all the information necessary for the unambiguous identification of the subscriber.
At the same SIM - cards can be programmed in advance, and then sold as a complete ready-to-eat product.
In principle, SIM - card could be made very simple and only include the identification number of the subscriber. But its creators soon realized it functions associated with authentication card (authentication) and encryption negotiation. That is, all the functions performed in other standards phone in GSM is divided between itself and the device SIM - card.
All clear "connected" operation (transmit and receive signals, their modulation and detection, play sounds and display characters on the display, and so on. N.) Are performed in the phone, and all that relates to personal data - is realized in the SIM - card. As a result of this approach perfectly working phone GSM independently (without SIM - card) provides the ability to perform only SOS calls to emergency services: police - police, fire and medical assistance.
The need to perform a SIM - card information processing has led to the implementation of the principle of its specialized calculator, containing all the essential elements of micro - computer: 8 - bit processor, input and output nodes of information, as well as permanent (ROM), operational (RAM) and reprogrammable (EEPROM) memory. It is non-volatile, but changes the EEPROM and placed all the information user and service.
By computing power SIM - cards are quite comparable with the first PC. As a result, in the SIM - cards began to be implemented, and many other functions: notebooks, capacity up to 100 or more phone numbers with names, lists of recent calls made and received, and so on. N.
Truly revolutionary change in any phone that supports the development phase of the standard GSM 2+ (here come almost all the models manufactured after 1998) commits created several years ago technology SIM Application Toolkit (STK). It is based on extensive use of information exchange SMS - messages and a special software applications that are written to the SIM - card in the form of a set of executable commands and procedures. Under the management of such programs becomes phone can automatically perform various action sequences. This can be a call to a particular number, send a short message to a certain number and certain contents, sending e-mail or fax, and so on.. All these procedures are, of course, can be performed manually, but automation of the process greatly simplifies and accelerates the use of such services . These may include: access to information - information services (weather, exchange rates, the latest news, the situation on the roads, and so on. N.), The management of connecting and disconnecting services used by your network, Internet access, payment of various services a mobile phone, and games. g.
From the standpoint of the user, the new technology is manifested in the fact that the phone installed STK - card, in addition to the standard for the machine set menu items, there is one more point - SIM - Menu (or SIM Service), which contains a list of additional features.
Their set is determined by your GSM network and can be changed (even quickly!) Without having to replace the phone or SIM - cards.
Thus, the current SIM - card - a versatile and high-tech device.
In order for the mobile phone could be served in a - a cellular network, it must be for it to "their" with a unique "name", for which the network will recognize it and refer to it. "Their" network phone becomes after registering his "name" in the subscriber base of the system.
Beginning with the earliest cellular systems, "name" phone usually had unique serial numbers of vehicles and their electronic counterparts - Electronic Serial Number (ESN).
It is this mobile phone number automatically and informs the network when accessing it to make the call.
Similarly, a call to the phone from the network passed on its ESN. Here - and then having childish problems.
Everything was very easy, when, for example, Ericsson created the first cellular network standard NMT - 450. For her, it supplied all the equipment from the network switch to mobile phones. Their rooms are, of course, have been known to produce. So all operations on "registration" on the network can be performed even at the factory. But then the number of cellular equipment manufacturers began to grow, and they used their own alpha - numeric designation serial number of vehicles. This eliminates any possibility of inconsistency simple and consistent record in the database. For "registration" phone it always had to be brought to the mobile operators. But this does not exclude the need to direct "contact" with the phone network equipment at his residence permit. Thus, at any change of telephone subscribers necessarily have to go with him in the service department of the cellular company.
First task is to solve this problem was faced by developers only have to create a new pan-European digital then cellular standards - GSM.
And they were invited to share the functions of identification equipment and subscribers.
For identification of GSM - phone used 15 - digit number unique International Mobile Equipment Identity (IMEI), assigned to each unit in the manufacture and tell them your network at the beginning of the exchange. He has also written on the package and on the phone itself - under the battery. The parameters of the called party were made in a special plug-in module - Subscriber Identity Module (SIM), inserted in the phone.
For design standard GSM, IMEI code equipment is used only for testing "legality" of telephones - cellular network fails in service "illegal" (ie, stolen) devices whose numbers appear in a special "stop list". Since the exchange of numbers all "suspicious" phones can be made directly between the cellular networks, the authorization for service of legal phone no need for any - any of their registration in the network, and the subscriber can change phones at their discretion. In addition, it should be noted that the examination itself and the IMEI code in GSM is optional and is not supported by all companies. As a result of this circumstance in the world and there is an underground market trade in stolen phones GSM.
Regarding SIM - cards, they contain all the information necessary for the unambiguous identification of the subscriber.
At the same SIM - cards can be programmed in advance, and then sold as a complete ready-to-eat product.
In principle, SIM - card could be made very simple and only include the identification number of the subscriber. But its creators soon realized it functions associated with authentication card (authentication) and encryption negotiation. That is, all the functions performed in other standards phone in GSM is divided between itself and the device SIM - card.
All clear "connected" operation (transmit and receive signals, their modulation and detection, play sounds and display characters on the display, and so on. N.) Are performed in the phone, and all that relates to personal data - is realized in the SIM - card. As a result of this approach perfectly working phone GSM independently (without SIM - card) provides the ability to perform only SOS calls to emergency services: police - police, fire and medical assistance.
The need to perform a SIM - card information processing has led to the implementation of the principle of its specialized calculator, containing all the essential elements of micro - computer: 8 - bit processor, input and output nodes of information, as well as permanent (ROM), operational (RAM) and reprogrammable (EEPROM) memory. It is non-volatile, but changes the EEPROM and placed all the information user and service.
By computing power SIM - cards are quite comparable with the first PC. As a result, in the SIM - cards began to be implemented, and many other functions: notebooks, capacity up to 100 or more phone numbers with names, lists of recent calls made and received, and so on. N.
Truly revolutionary change in any phone that supports the development phase of the standard GSM 2+ (here come almost all the models manufactured after 1998) commits created several years ago technology SIM Application Toolkit (STK). It is based on extensive use of information exchange SMS - messages and a special software applications that are written to the SIM - card in the form of a set of executable commands and procedures. Under the management of such programs becomes phone can automatically perform various action sequences. This can be a call to a particular number, send a short message to a certain number and certain contents, sending e-mail or fax, and so on.. All these procedures are, of course, can be performed manually, but automation of the process greatly simplifies and accelerates the use of such services . These may include: access to information - information services (weather, exchange rates, the latest news, the situation on the roads, and so on. N.), The management of connecting and disconnecting services used by your network, Internet access, payment of various services a mobile phone, and games. g.
From the standpoint of the user, the new technology is manifested in the fact that the phone installed STK - card, in addition to the standard for the machine set menu items, there is one more point - SIM - Menu (or SIM Service), which contains a list of additional features.
Their set is determined by your GSM network and can be changed (even quickly!) Without having to replace the phone or SIM - cards.
Thus, the current SIM - card - a versatile and high-tech device.
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