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. Mobile radio telephone systems preceded modern cellular mobile telephony technology. ... Push-to-Talk (PTT), also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode. ... The Mobile Telephone System (MTS) was one of the earliest mobile telephone standards. ... The Improved Mobile Telephone Service (IMTS) is a pre-cellular VHF/UHF radio system that links to the PSTN. IMTS was the radiotelephone equivalent of land dial phone service. ... The Advanced Mobile Telephone System was a 0G method of radio communication, mainly used in Japanese portable radio systems. ... OLT (Norwegian for Offentlig Landmobil Telefoni, Public Land Mobile Telephony), was the first land mobile telephone network in Norway. ... MTD (Swedish abbreviation for Mobilelefonisystem D, or Mobile telephony system D) was a manual mobile phone system for the 450 MHz frequency band. ... Autotel (also called PALM, or Public Automated Land Mobile) is a radiotelephone service which was the missing link between earlier MTS/IMTS and later cellular telephone services. ... ARP (Autoradiopuhelin, Car Radio Phone in English) was the first commercially operated public mobile phone network in Finland. ... 1G (or 1-G) is short for first-generation wireless telephone technology, cellphones. ... For other meanings of the abbreviation, see: NMT. NMT (Nordisk MobilTelefoni or Nordiska MobilTelefoni-gruppen, Nordic Mobile Telephone in English) is a mobile phone system that was specified by the Nordic telecommunications administrations (PTTs) starting in 1970, and opened for service in 1981 as a response to the increasing congestion... Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1983[1][2] It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s, and is still... hicap is a mobile techonology which has a consumer interface with a wide variety of industry references. ... Cellular Digital Packet Data (CDPD) uses unused bandwidth normally used by AMPS mobile phones between 800 and 900 MHz to transfer data. ... Cingular Interactive Truck at Ground Zero on 9/11/2001 Mobitex Network Design Mobitex is an OSI based open standard, national public access wireless data network first introduced in 1991 by carriers RAM Mobile Data and in Canada 1990 by Rogers Cantel. ... DataTac is a wireless data network technology originally developed by Motorola and deployed in the United States as the ARDIS network. ... This article does not cite any references or sources. ... The Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. ... Iden is also a village in East sussex, England iDEN Base Radio at a Cell Site Integrated Digital Enhanced Network (iDEN) is a mobile telecommunications technology, it is known to eat little children, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. ... IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS). ... Interim Standard 95 (IS-95), is the first CDMA-based digital cellular standard pioneered by Qualcomm. ... Personal Digital Cellular (PDC) is a 2G mobile phone standard developed and used exclusively in Japan. ... Circuit Switched Data, often known as CSD, is the original form of data transmission developed for the GSM mobile phone system. ... The Personal Handy-phone System (PHS), also marketed as the Personal Access System (PAS), is a mobile network system operating in the 1880-1930 MHz frequency band. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM and IS-136 mobile phones. ... High-Speed Circuit-Switched Data (HSCSD), is a development of Circuit Switched Data, the original data transmission mechanism of the GSM mobile phone system. ... Wideband Integrated Dispatch Enhanced Network, or WiDEN, is a software upgrade developed by Motorola for its iDEN enhanced specialized mobile radio (or ESMR) wireless telephony protocol. ... CDMA2000 is a hybrid 2. ... This article does not cite any references or sources. ... Enhanced Data rates for GSM Evolution (EDGE) or Enhanced GPRS (EGPRS), is a digital mobile phone technology that allows it to increase data transmission rate and improve data transmission reliability. ... W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ... FOMA, officially short for Freedom of Mobile Multimedia Access, is the brand name for the 3G services being offered by Japanese mobile phone operator NTT DoCoMo. ... UMTS-TDD is a mobile data network standard built upon the UMTS 3G cellular mobile phone standard, using a TD-CDMA, TD-SCDMA, or other 3GPP-approved, air interface that uses Time Division Duplexing to duplex spectrum between the up-link and down-link. ... UMTS-TDD is a mobile data network standard built upon the UMTS 3G cellular mobile phone standard, using a TD-CDMA, TD-SCDMA, or other 3GPP-approved, air interface that uses Time Division Duplexing to duplex spectrum between the up-link and down-link. ... Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO and often EV, is one telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. ... TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) is a 3G mobile telecommunications standard, being pursued in the Peoples Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang and Siemens AG, in an attempt to develop home-grown technology and not be dependent on Western... The Generic Access Network (GAN) was formerly known as Unlicensed Mobile Access (UMA), until it was adopted by the 3GPP in April 2005. ... High-Speed Packet Access (HSPA) is a collection of mobile telephony protocols that extend and improve the performance of existing UMTS protocols. ... High-Speed Downlink Packet Access (HSDPA, also known as High-Speed Downlink Protocol Access) is a 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access (HSPA) family, which allows networks based on Universal Mobile Telecommunications System (UMTS) to have higher data transfer speeds and capacity. ... High-Speed Uplink Packet Access (HSUPA) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 5. ... HSPA+ (or HSPA Evolution) is a 3G mobile telephony protocol defined in 3GPP release 7 (expected in 2007). ... High Speed OFDM Packet Access (HSOPA) is a proposed part of 3GPPs Long Term Evolution (LTE) upgrade path for UMTS systems. ... ‹ The template below (Expand) is being considered for deletion. ... iBurst (or HC-SDMA, High Capacity Spatial Division Multiple Access) is a wireless broadband technology developed by ArrayComm. ... HIPERMAN stands for High Performance Radio Metropolitan Area Network and is a standard created by the European Telecommunications Standards Institute (ETSI) Broadband Radio Access Networks (BRAN) group to provide a wireless network communication in the 2 - 11 GHz bands across Europe and other countries which follow the ETSI standard. ... Ultra Mobile Broadband is the brand name to describe the advanced technologies and services that will be supported by the CDMA2000 1xEV-DO Revision C (Rev. ... 3GPP LTE (Long Term Evolution) is the name given to a project within the Third Generation Partnership Project to improve the UMTS mobile phone standard to cope with future requirements. ... WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. ... WiBro (Wireless Broadband, Korean: 와이브로) is a wireless broadband Internet technology being developed by the Korean telecoms industry. ... Cellular frequencies - the general term which unites radio frequencies utilized by cellular networks to provide service to their subscribers. ... The Specialized Mobile Radio system (SMR) is a conventional two-way radio system, or trunked radio system, operated by a service in the 800 or 900 Mhz bands. ... Cellular frequencies - the general term which unites radio frequencies utilized by cellular networks to provide service to their subscribers. ... Personal Communications Service or PCS is the name for the 1900-MHz radio band used for digital mobile phone services in Canada and the United States. ... Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ... The public switched telephone network (PSTN) is the network of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the network of the worlds public IP-based packet-switched networks. ... A mobile phone operator (also wireless carrier) is a telephone company that provides phone services for mobile phone subscribers. ... This article or section includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... A telecommunications network is a network of telecommunications links arranged so that messages may be passed from one part of the network to another over multiple links. ... A telephone operator manually connecting calls with patch cables at a telephone switchboard. ... Mobility Management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. ...

The Network Switching Subsystem, also referred to as the GSM core network, usually refers to the circuit-switched core network, used for traditional GSM services such as voice calls, SMS, and Circuit Switched Data calls. GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... This article describes the technical methods for providing the text messaging service. ... Circuit Switched Data, often known as CSD, is the original form of data transmission developed for the GSM mobile phone system. ...

There is also an overlay architecture on the GSM core network to provide packet-switched 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 GPRS system is used by GSM Mobile phones, the most common mobile phone system in the world (as of 2004), for transmitting IP packets. ... WAP is an open international standard for applications that use wireless communication. ... Multimedia Messaging Service (MMS) is a standard for telephony messaging systems that allows sending messages that include multimedia objects (images, audio, video, rich text) and not just text as in Short Message Service (SMS). ...

All mobile phones manufactured today have both circuit and packet based services, so most operators have a GPRS network in addition to the standard GSM core network.

Mobile Switching Centre (MSC)

Description

The Mobile Switching Centre or MSC is a sophisticated telephone exchange which provides circuit-switched calling, mobility management, and GSM services to the mobile phones roaming within the area that it serves. This means voice, data and fax services, as well as SMS and call divert. A telephone operator manually connecting calls with patch cables at a telephone switchboard. ... Mobility Management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. ... GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ... This article describes the technical methods for providing the text messaging service. ...

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 re-coded into an "analogue" signal (although actually this will almost certainly mean sound encoded digitally as PCM signal in a 64-kbit/s timeslot, known as a DS0 in America). Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code. ... In T-carrier systems Digital signal 0 (DS0) is a basic digital signaling rate of 64 kb/s, corresponding to the capacity of one voice-frequency-equivalent channel. ...

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 public switched telephone network (PSTN) is the network of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the network of the worlds public IP-based packet-switched networks. ... The Base Station Subsystem (BSS) is the section of a GSM network which is responsible for handling traffic and signaling between a mobile phone and the Network Switching Subsystem. ...

The Visited MSC is the MSC where a customer is currently located. The VLR associated with this MSC will have the subscriber's data in it.

The Anchor MSC is the MSC from which a handover has been initiated. The Target MSC is the MSC toward which a Handover should take place. An MSC Server is a part of the redesigned MSC concept starting from 3GPP Release 5. In telecommunication, the term handoff refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another. ...

Mobile Switching Centre Server (MSC-S)

Description

The Mobile Switching Centre Server or MSC Server is a soft switch variant of Mobile Switching Centre, which provides circuit-switched calling, mobility management, and GSM services to the mobile phones roaming within the area that it serves. MSC Server functionality enables split between control (signalling) and user plane (bearer in network element called as Media Gateway), which guarantees more optimal placement of network elements within the network. Mobility Management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. ... GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ...

MSC Server and MGW Media Gateway makes it possible to cross-connect circuit switched calls switched by using IP, ATM AAL2 as well as TDM. A Media Gateway acts as a translation unit between disparate telecommunications networks such as PSTN; Next Generation Networks; 2G, 2. ...

More information is available in 3GPP TS 23.205.

Other GSM Core Network Elements connected to the MSC

The MSC connects to the following elements:

• The HLR for obtaining data about the SIM and MSISDN
• the Base Station Subsystem which handles the radio communication with 2G and 2.5G mobile phones.
• the UTRAN which handles the radio communication with 3G mobile phones.
• the VLR for determining where other mobile subscribers are located.
• other MSCs for procedures such as handover.

The GSM Core network is the heart of a GSM system, the most common mobile phone system in the world. ... A Cingular Wireless mini SIM card. ... The Mobile Station Integrated Services Digital Network (MSISDN) is the mobile equivalent of ISDN. Used as a value, MSISDN refers to the MSISDN subscriber ID, which is a max 15-digit number. ... The Base Station Subsystem (BSS) is the section of a GSM network which is responsible for handling traffic and signaling between a mobile phone and the Network Switching Subsystem. ... This article does not cite any references or sources. ... 2. ... UTRAN, short for UMTS Terrestrial Radio Access Network, is a collective term for the Node-Bs and Radio Network Controllers which make up the UMTS radio access network. ... This article does not cite any references or sources. ... In telecommunication, the term handoff refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another. ...

Procedures implemented

Tasks of the MSC include

• delivering calls to subscribers as they arrive based on information from the VLR
• connecting outgoing calls to other mobile subscribers or the PSTN.
• delivering SMSs from subscribers to the SMSC and vice versa
• arranging handovers from BSC to BSC
• carrying out handovers from this MSC to another
• supporting supplementary services such as conference calls or call hold.
• collecting billing information.

GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... The public switched telephone network (PSTN) is the concatenation of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the concatenation of the worlds public IP-based packet-switched networks. ... This article describes the technical methods for providing the text messaging service. ... A Short Message Service Center (SMSC) is a network element in the mobile telephone network which delivers SMS messages. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Home Location Register (HLR)

Description

The Home Location Register or HLR is a central database that contains details of each mobile phone subscriber that is authorized to use the GSM core network.

There is one HLR in one Public Land Mobile Network. HLR is a single database but can be maintained as separate databases when the data to be stored is more than the capacity. In telecommunication, a public land mobile network (PLMN) is a network that is established and operated by an administration or by a recognized operating agency (ROA) for the specific purpose of providing land mobile telecommunications services to the public. ...

More precisely, the HLR stores details of every SIM card issued by the mobile phone operator. Each SIM has a unique identifier called an IMSI which is one of the primary keys to each HLR record. SIM re-directs here; for alternate uses see Sim (disambiguation) A SIM card taken from a GSM mobile phone A subscriber identity module (SIM) is a smartcard securely storing the key identifying a mobile subscriber. ... A mobile phone operator (also wireless carrier) is a telephone company that provides phone services for mobile phone subscribers. ... IMSI IMSI is an acronym for International Mobile Subscriber Identity. ... In database design, a primary key is a value that can be used to identify a unique row in a table. ...

The next important items of data associated with the SIM are the telephone numbers used to make and receive calls to the mobile phone, known as MSISDNs. The main MSISDN is the number used for making and receiving voice calls and SMS, but it is possible for a SIM to have other secondary MSISDNs associated with it for fax and data calls. Each MSISDN is also a primary key to the HLR record. A telephone number is a sequence of decimal digits that uniquely indicates the network termination point. ... The Mobile Station Integrated Services Digital Network (MSISDN) is the mobile equivalent of ISDN. Used as a value, MSISDN refers to the MSISDN subscriber ID, which is a max 15-digit number. ... A Samsung fax machine Fax (short for facsimile, from Latin fac simile, make similar, i. ... In database design, a primary key is a value that can be used to identify a unique row in a table. ...

Examples of other data stored in the HLR in a SIM record is: Look up SIM, Sim, sim in Wiktionary, the free dictionary. ...

• GSM services that the subscriber has requested or been given
• GPRS settings to allow the subscriber to access packet services
• Current Location of subscriber (VLR and SGSN)
• Call divert settings applicable for each associated MSISDN.

The HLR data is stored for as long as a subscriber remains with the mobile phone operator. GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM mobile phones. ... The GSM Core network is the heart of a GSM system, the most common mobile phone system in the world. ... The GPRS system is used by GSM Mobile phones, as of 2004 the most common mobile phone system in the world, for transmitting IP packets. ... Call forwarding (or call diverting), in telephony, is a feature on some telephone networks that allows an incoming call to a called party, which would be otherwise unavailable, to be redirected to a mobile telephone or other telephone number where the desired called party is situated. ... The Mobile Station Integrated Services Digital Network (MSISDN) is the mobile equivalent of ISDN. Used as a value, MSISDN refers to the MSISDN subscriber ID, which is a max 15-digit number. ... A mobile phone operator (also wireless carrier) is a telephone company that provides phone services for mobile phone subscribers. ...

At first glance, the HLR seems to be just a database which is merely accessed by other network elements which do the actual processing for mobile phone services. In fact the HLR is a system which directly receives and processes MAP transactions and messages. If the HLR fails, then the mobile network is effectively disabled as it is the HLR which manages the Location Updates as mobile phones roam around. GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... Mobile Application Part ... Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ...

As the number of mobile subscribers has grown in mobile phone operators the HLR has become a more powerful computer server rather than the traditional telephone exchange hardware in the early days of GSM. A mobile phone operator (also wireless carrier) is a telephone company that provides phone services for mobile phone subscribers. ... This article does not cite any references or sources. ... A telephone operator manually connecting calls with patch cables at a telephone switchboard. ... Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ...

Other GSM Core Network Elements connected to the HLR

The HLR connects to the following elements:

• the Gateway MSC (G-MSC) for handling incoming calls
• The VLR for handling requests from mobile phones to attach to the network
• The SMSC for handling incoming SMS
• The voice mail system for delivering notifications to the mobile phone that a message is waiting

Voicemail (or voice mail; abbreviated v-mail or vmail) is a specific application of an interactive voice response system. ...

Procedures implemented

The main function of the HLR is to manage the fact that SIMs and phones move around a lot. The following procedures are implemented to deal with this: Mobility Management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. ...

• Manage the mobility of subscribers by means of updating their position in administrative areas called 'location areas', which are identified with a LAC. The action of a user of moving from one LA to another is followed by the HLR with a Location area update while retrieving information from BSS as BSIC (cell identifier).
• Send the subscriber data to a VLR or SGSN when a subscriber first roams there.
• Broker between the GMSC or SMSC and the subscriber's current VLR in order to allow incoming calls or text messages to be delivered.
• Remove subscriber data from the previous VLR when a subscriber has roamed away from it.

Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ... The GSM Core network is the heart of a GSM system, the most common mobile phone system in the world. ... A Short Message Service Center (SMSC) is a network element in the mobile telephone network which delivers SMS messages. ... GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ... Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ...

Authentication Centre (AUC)

Description

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. Authentication (from Greek αυθεντικός; real or genuine, from authentes; author) is the act of establishing or confirming something (or someone) as authentic, that is, that claims made by or about the thing are true. ... SIM re-directs here; for alternate uses see Sim (disambiguation) A SIM card taken from a GSM mobile phone A subscriber identity module (SIM) is a smartcard securely storing the key identifying a mobile subscriber. ... This article is about algorithms for encryption and decryption. ...

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. SIM re-directs here; for alternate uses see Sim (disambiguation) A SIM card taken from a GSM mobile phone A subscriber identity module (SIM) is a smartcard securely storing the key identifying a mobile subscriber. ... A mobile phone operator (also wireless carrier) is a telephone company that provides phone services for mobile phone subscribers. ...

Proper implementation of security in and around the AUC is a key part of an operator's strategy to avoid SIM cloning. SIM cloning consists of (often illegally) duplicating the GSM Subscriber Identity Module (a SIM card must be entered into a GSM phone in order for it to connect to a network, except for the basic GSM emergency 112 calls or local emergency calls (like emergency 911 calls for the United...

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 challenge/response for identification purposes and an encryption key called Kc for use in over the air communications. IMSI IMSI is an acronym for International Mobile Subscriber Identity. ...

Other GSM Core Network Elements connected to the AUC

The AUC connects to the following elements:

• the MSC which requests a new batch of triplet data for an IMSI after the previous data have been used. This ensures that same keys and challenge responses are not used twice for a particular mobile.

Procedures implemented

The AUC stores the following data for each IMSI:

• the Ki
• Algorithm id (the standard algorithms are called A3 or A8, but an operator may choose a proprietary one).

When the MSC asks the AUC for a new set of triplets for a particular IMSI, the AUC first generates a random number known as RAND. This RAND is then combined with the Ki to produce two numbers as follows:

• The Ki and RAND are fed into the A3 algorithm and a number known as Signed RESponse or SRES is calculated.
• The Ki and RAND are fed into the A8 algorithm and a session key called Kc is calculated.

The numbers (RAND, SRES, KC) form the triplet sent back to the MSC. When a particular IMSI requests access to the GSM core network, the MSC sends the RAND part of the triplet to the SIM. The SIM then feeds this number and the Ki (which is burned onto the SIM) into the A3 algorithm as appropriate and an SRES is calculated and sent back to the MSC. If this SRES matches with the SRES in the triplet (which it should if it is a valid SIM), then the mobile is allowed to attach and proceed with GSM services. GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ...

After successful authentication, the MSC sends the encryption key Kc to the Base Station Controller (BSC) so that all communications can be encrypted and decrypted. Of course, the mobile phone can generate the Kc itself by feeding the same RAND supplied during authentication and the Ki into the A8 algorithm. The Base Station Subsystem (BSS) is the section of a GSM network which is responsible for handling traffic and signaling between a mobile phone and the Network Switching Subsystem. ...

The AUC is usually collocated with the HLR, although this is not necessary. Whilst the procedure is secure for most everyday use, it is by no means crack proof. Therefore a new set of security methods was designed for 3G phones. This article does not cite any references or sources. ...

Visitor Location Register (VLR)

Description

The Visitor Location Register or VLR is a temporary database of the subscribers who have roamed into the particular area which it serves. Each Base Station in the network is served by exactly one VLR, hence a subscriber cannot be present in more than one VLR at a time. Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ... A typical BTS tower which holds the antenna. ...

The data stored in the VLR has either been received from the HLR, or collected from the MS. In practice, for performance reasons, most vendors integrate the VLR directly to the V-MSC and, where this is not done, the VLR is very tightly linked with the MSC via a proprietary interface.

Data stored includes:

• IMSI (the subscriber's identity number)
• authentication data
• MSISDN (the subscriber's phone number)
• GSM services that the subscriber is allowed to access
• Access Point (GPRS) subscribed
• the HLR address of the subscriber

IMSI IMSI is an acronym for International Mobile Subscriber Identity. ... The Mobile Station Integrated Services Digital Network (MSISDN) is the mobile equivalent of ISDN. Used as a value, MSISDN refers to the MSISDN subscriber ID, which is a max 15-digit number. ... GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ...

Other GSM Core Network Elements connected to the VLR

The VLR connects to the following elements:

• the Visited MSC (V-MSC) to pass data needed by the V-MSC during its procedures, e.g. authentication or call setup.
• The HLR to request data for mobile phones attached to its serving area.
• Other VLRs to transfer temporary data concerning the mobile when they roam into new VLR areas (for example TMSI which is an ephemeral temporary IMSI used in communication).

Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ... This page covers Mobility Management in GSM and UMTS networks including those functions related to GPRS. Mobility Management is one of the major functions of a GSM or UMTS Network. ... IMSI IMSI is an acronym for International Mobile Subscriber Identity. ...

Procedures implemented

The primary functions of the VLR are:

• to inform the HLR that a subscriber has arrived in the particular area covered by the VLR
• to track where the subscriber is within the VLR area (location area) when no call is ongoing
• to allow or disallow which services the subscriber may use
• to allocate roaming numbers during the processing of incoming calls
• to purge the subscriber record if a subscriber becomes inactive whilst in the area of a VLR. The VLR deletes the subscriber's data after a fixed time period of inactivity and informs the HLR (e.g. when the phone has been switched off and left off or when the subscriber has moved to an area with no coverage for a long time).
• to delete the subscriber record when a subscriber explicitly moves to another, as instructed by the HLR

GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. ...

EIR

The EIR (Equipment Identity Register) is often integrated to the HLR. The EIR keeps a list of mobile phones (identified by their IMEI) which are to be banned from the network or monitored. This is designed to allow tracking of stolen mobile phones. In theory all data about all stolen mobile phones should be distributed to all EIRs in the world through a Central EIR. It is clear, however, that there are some countries where this is not in operation. The EIR data does not have to change in real time, which means that this function can be less distributed than the function of the HLR. Eir (help or mercy) is, in Norse mythology, a goddess of the Æsir; she knew the medicinal properties of herbs and was capable of resurrection. ... The International Mobile Equipment Identity (or IMEI) is a unique number associated with every GSM and UMTS mobile phone. ...

Other support functions

Connected more or less directly to the GSM core network are many other functions.

BC

The Billing Centre is responsible for processing the toll tickets generated by the VLRs and HLRs and generating a bill for each subscriber. it is also responsible for to generate billing data of roaming subscriber.

SMSC

The Short Message Service Centre supports the sending and reception oftext messages. A Short Message Service Center (SMSC) is a network element in the mobile telephone network which delivers SMS messages. ...

MMSC

The Multimedia Messaging System Centre supports the sending of multimedia messages (e.g. Images, Audio, Video and their combinations) to (or from) MMS-enabled Handsets. Multimedia Messaging System (MMS) is a system of transmitting not only text messages, but also various kinds of multimedia contents (e. ... Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... This article does not cite any references or sources. ...

VMS

The Voicemail System records and stores voicemails. Voicemail (or voice mail, vmail or VMS, sometimes called messagebank) is a centralized system of managing telephone messages for a large group of people. ...

Lawful interception functions

According to U.S. law, which has also been copied into many other countries, especially in Europe, all telecommunications equipment must provide facilities for monitoring the calls of selected users. There must be some level of support for this built into any of the different elements. The concept of lawful interception is also known, following the relevant U.S. law, as CALEA. Generally Lawful Interception implementation is similar to the implementation of conference call.While A and B is talking with each other, C can join the call and listens silently. The Communications Assistance for Law Enforcement Act (CALEA) is a controversial United States wiretapping law passed in 1994 (Pub. ...

See also

The GPRS Core Network with the rest of the GSM core network. The GPRS system is used by GSM Mobile phones, the most common mobile phone system in the world (as of 2004), for transmitting IP packets. ...

External links

• the 3GPP, the standardisation body for GSM and UMTS
• Telcoware HLR
• Switchlab HLR