Roaming is a wireless telecommunication term typically used with mobile devices, such as mobile phones . It refers to a mobile phone being used outside the range of its native network and connecting to another available cell network .
101-523: In more technical terms, roaming refers to the ability for a cellular customer to automatically make and receive voice calls, send and receive data, or access other services, including home data services, when travelling outside the geographical coverage area of the home network , by means of using a visited network . For example: should a subscriber travel beyond their cell phone company's transmitter range, their cell phone would automatically hop onto another phone company's service, if available. The process
202-508: A cellular radio system, a land area to be supplied with radio service is divided into cells in a pattern dependent on terrain and reception characteristics. These cell patterns roughly take the form of regular shapes, such as hexagons, squares, or circles although hexagonal cells are conventional. Each of these cells is assigned with multiple frequencies ( f 1 – f 6 ) which have corresponding radio base stations . The group of frequencies can be reused in other cells, provided that
303-458: A pay-as-you-go ( PAYG ), pay-as-you-talk , pay and go , go-phone , prepay , or burner phone , is a mobile device such as a phone for which credit is purchased in advance of service use. The purchased credit is used to pay for telecommunications services at the point the service is accessed or consumed. If there is no credit, then access is denied by the cellular network or Intelligent Network . Users can top up their credit at any time using
404-642: A WLAN to a WLAN or a GSM network to a GSM network, has already been described above and is likewise defined by the foreignness of the network based on the type of subscriber entry in the home subscriber register. In the case of session continuity, seamless access to these services across different access types is provided. The term "roaming", also known as "e-roaming", is a concept for charging battery electric vehicles (BEVs) at other charging stations. In practice, e-roaming allows EV drivers to achieve greater interoperability by providing access to public charging points from any owner/operator's EV charging network through
505-600: A call. This charge is called a flagfall charge. In the European Union , regulation on roaming charges began on 30 June 2007, forcing service providers to lower their roaming fees across the 28-member bloc. It later also included EEA member states. The regulation set a price cap of €0.39 (€0.49 in 2007, €0.46 in 2008, €0.43 in 2009) per minute for outgoing calls, and €0.15 (€0.24 in 2007, €0.22 in 2008, €0.19 in 2009) per minute for incoming calls - excluding tax. Having still found that market conditions did not justify lifting
606-470: A common platform and a single network subscription or contract. There are proprietary (closed) charging networks, such as Tesla Superchargers , or providers sharing charging points through contracts and agreements. Thus, the EV can "roam" between those charging points. "Home network" refers to the network the subscriber is registered with. "Visitor network" refers to the network a subscriber roams temporarily and
707-458: A draft report proposing coordinated action on roaming services. This was followed by a final report in February 2013 recommending that the two countries equip their telecommunications regulators with an extended palette of regulatory remedies, when they investigate international roaming. The Australian and New Zealand prime ministers subsequently announced that they would introduce legislation to effect
808-403: A free unlimited mobile to mobile feature. Most mobile phone operators will require the customer's living or billing address be inside their coverage area or less often inside the government issued radio frequency license of the mobile phone operator, this is usually determined by a computer estimate because it is impossible to guarantee coverage . If a potential customer's address is not within
909-513: A frequency reuse of 1. Since such systems do not spread the signal across the frequency band, inter-cell radio resource management is important to coordinate resource allocation between different cell sites and to limit the inter-cell interference. There are various means of inter-cell interference coordination (ICIC) already defined in the standard. Coordinated scheduling, multi-site MIMO or multi-site beamforming are other examples for inter-cell radio resource management that might be standardized in
1010-399: A large number of active phones in that area. All of the cell sites are connected to telephone exchanges (or switches), which in turn connect to the public telephone network . In cities, each cell site may have a range of up to approximately 1 ⁄ 2 mile (0.80 km), while in rural areas, the range could be as much as 5 miles (8.0 km). It is possible that in clear open areas,
1111-477: A larger number of devices, enabling advanced applications in fields such as healthcare, transportation, and smart cities . Private cellular networks can be used for research or for large organizations and fleets, such as dispatch for local public safety agencies or a taxicab company, as well as for local wireless communications in enterprise and industrial settings such as factories, warehouses, mines, power plants, substations, oil and gas facilities and ports. In
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#17330860349791212-468: A limited, shared resource. Cell-sites and handsets change frequency under computer control and use low power transmitters so that the usually limited number of radio frequencies can be simultaneously used by many callers with less interference. A cellular network is used by the mobile phone operator to achieve both coverage and capacity for their subscribers. Large geographic areas are split into smaller cells to avoid line-of-sight signal loss and to support
1313-424: A lower cost (often for low usage patterns e.g. a telephone for emergency use) and make it easier to control spending by limiting debt and controlling usage. They often have fewer contractual obligations – no early termination fee, freedom to change providers, plans, able to be used by those unable to take out a contract (i.e. under age of majority). Depending on local laws, they may be available to those who do not have
1414-650: A minimum of three channels, and three towers for each cell and greatly increases the chances of receiving a usable signal from at least one direction. The numbers in the illustration are channel numbers, which repeat every 3 cells. Large cells can be subdivided into smaller cells for high volume areas. Cell phone companies also use this directional signal to improve reception along highways and inside buildings like stadiums and arenas. Practically every cellular system has some kind of broadcast mechanism. This can be used directly for distributing information to multiple mobiles. Commonly, for example in mobile telephony systems,
1515-414: A mobile account call it "churn". In the early years, a prepaid mobile phone could only be used within the network of the operator from which the customer purchased the phone. It was not possible to roam onto other GSM networks when using the phone abroad. This was because the operator had no way to bill calls in real time from another network. However, most prepaid phones now offer roaming using one of
1616-402: A mobile phone network manages handover). The most common example of a cellular network is a mobile phone (cell phone) network. A mobile phone is a portable telephone which receives or makes calls through a cell site (base station) or transmitting tower. Radio waves are used to transfer signals to and from the cell phone. Modern mobile phone networks use cells because radio frequencies are
1717-628: A number of desirable features: Major telecommunications providers have deployed voice and data cellular networks over most of the inhabited land area of Earth . This allows mobile phones and other devices to be connected to the public switched telephone network and public Internet access . In addition to traditional voice and data services, cellular networks now support Internet of Things (IoT) applications, connecting devices such as smart meters , vehicles, and industrial sensors. The evolution of cellular networks from 1G to 5G has progressively introduced faster speeds, lower latency, and support for
1818-412: A number of frequency channels corresponding to a bandwidth of B/K , and each sector can use a bandwidth of B/NK . Code-division multiple access -based systems use a wider frequency band to achieve the same rate of transmission as FDMA, but this is compensated for by the ability to use a frequency reuse factor of 1, for example using a reuse pattern of 1/1. In other words, adjacent base station sites use
1919-611: A per-minute basis for wireless voice service, per text message sent and received and per megabyte of data used for data service, and they are typically determined by the service provider's pricing plan. Several carriers in both the United States and India have eliminated these fees in their nationwide pricing plans. All of the major carriers now offer pricing plans that allow consumers to purchase nationwide roaming-free minutes. However, carriers define "nationwide" in different ways. For example, some carriers define "nationwide" as anywhere in
2020-599: A permanent address, phone number, or credit card. This makes them popular among travelers and students away from their hometowns. Additionally, they are popular with parents who wish to have a way to stay connected with their college age students and have some control over the costs. Sometimes, pay-as-you-go customers pay more for their calls, SMS and data than contract customers. In some cases they are limited in what they can do with their phone – calls to international or premium-rate telephone numbers may be blocked, and they may not be able to roam . These limitations are usually
2121-471: A phone to work in a country with a different frequency allocation, it must support one or both of that country's frequencies, and thus be tri or quad band . If international roaming allows the traveler to stay connected during their trip, it can also generate significant costs for users, due to the trend of carriers pricing GSM usage internationally outrageously high if the traveler elects to not purchase an optional addon to their current phone service. In fact,
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#17330860349792222-421: A rolling contract or a 30-day contract) and billing arrangement with a mobile phone operator ( mobile virtual network operator or mobile network operator ). A prepaid mobile phone provides most of the services offered by a mobile phone operator . The main difference is that with prepaid phones, payment for service is made before use. As calls and texts are made, and as data is used, deductions are made against
2323-463: A smartphone. United States Senators Chuck Schumer (D-NY) and John Cornyn (R-TX) introduced legislation requiring consumers to produce identification before buying pre-paid phones in 2010, which was not passed. In an effort to differentiate the prepaid from post-paid service for their customers, CSPs have branded prepaid services differently from the post-paid services. A variant of post-paid service has emerged in recent years that comes closer to
2424-479: A standard frequency-division multiple access (FDMA) system. Consider the case of a taxi company, where each radio has a manually operated channel selector knob to tune to different frequencies. As drivers move around, they change from channel to channel. The drivers are aware of which frequency approximately covers some area. When they do not receive a signal from the transmitter, they try other channels until finding one that works. The taxi drivers only speak one at
2525-482: A subscriber to have a credit balance in the account to make outgoing calls (except emergency calls , which are always allowed). In the US, incoming calls are also barred, while in some other countries, a prepaid mobile with zero balance may still receive calls and texts. This results in an "on/off" or "all or nothing" proposition for the prepaid service providers and their clients (i.e. the account either has enough credit to use
2626-526: A time when invited by the base station operator. This is a form of time-division multiple access (TDMA). The history of cellular phone technology began on December 11, 1947 with an internal memo written by Douglas H. Ring , a Bell Labs engineer in which he proposed development of a cellular telephone system by AT&T. The first commercial cellular network, the 1G generation, was launched in Japan by Nippon Telegraph and Telephone (NTT) in 1979, initially in
2727-416: A user may receive signals from a cell site 25 miles (40 km) away. In rural areas with low-band coverage and tall towers, basic voice and messaging service may reach 50 miles (80 km), with limitations on bandwidth and number of simultaneous calls. Since almost all mobile phones use cellular technology , including GSM , CDMA , and AMPS (analog), the term "cell phone" is in some regions, notably
2828-413: A variety of payment mechanisms. ("Pay-as-you-go", "PAYG", and similar terms are also used for other non-telecommunications services paid for by advance deposit.) The alternative billing method (and what is commonly referred to as a mobile contract) is the postpaid mobile phone , where a user enters into a long-term contract (lasting 12, 18, or 24 months) or short-term contract (also commonly referred to as
2929-460: A year of non-use. By 2003, the number of prepaid accounts grew past contract accounts, and by 2007, two-thirds of all mobile phone accounts worldwide were prepaid accounts. The history of prepaid mobile phones begins in the 1990s, when larger markets were being sought after by the mobile phone operators . Before this date, all mobile phone services were offered on a post-paid basis , which excluded people with poor credit. Prepaid mobile service
3030-412: Is wireless and the network is distributed over land areas called cells , each served by at least one fixed-location transceiver (such as a base station ). These base stations provide the cell with the network coverage which can be used for transmission of voice, data, and other types of content via radio waves . Each cell's coverage area is determined by factors such as the power of the transceiver,
3131-487: Is a common practice) pair depends on the switch and its location. Hence, software changes and a greater processing capability are required, but furthermore this situation could introduce the fairly new concept of roaming on a per MSC basis instead of per Operator basis. But this is actually a burden, so it is avoided. This type refers to customers who purchase service with a mobile phone operator intending to permanently roam, or be off-network. This becomes possible because of
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3232-534: Is a concern by police and security agencies that anonymous use of prepaid mobile services facilitates criminal or terrorist activities. Prepaid phone users can be anonymous for two reasons: While there is no doubt that criminals and terrorists use prepaid SIM cards to help stay anonymous and avoid easy detection, to date there has been no empirical evidence to indicate that: In fact, a publicly available policy assessment report from Mexico showed that mandatory SIM registration introduced there in 2009 had failed to help
3333-550: Is based on spread spectrum technology developed for military use during World War II and improved during the Cold War into direct-sequence spread spectrum that was used for early CDMA cellular systems and Wi-Fi . DSSS allows multiple simultaneous phone conversations to take place on a single wideband RF channel, without needing to channelize them in time or frequency. Although more sophisticated than older multiple access schemes (and unfamiliar to legacy telephone companies because it
3434-424: Is called the handover or handoff. Typically, a new channel is automatically selected for the mobile unit on the new base station which will serve it. The mobile unit then automatically switches from the current channel to the new channel and communication continues. The exact details of the mobile system's move from one base station to the other vary considerably from system to system (see the example below for how
3535-612: Is high and the country is divided into telecom circles , this type of roaming is common. Following the launch of the Pebble Network in the UK on 15 July 2015, national roaming has been possible across the major UK networks at no additional cost using a Pebble Network SIM card. This type of roaming refers to the ability to move to a foreign service provider's network. It is, consequently, of particular interest to international tourists and business travelers. Broadly speaking, international roaming
3636-478: Is no problem with two cells sufficiently far apart operating on the same frequency, provided the masts and cellular network users' equipment do not transmit with too much power. The elements that determine frequency reuse are the reuse distance and the reuse factor. The reuse distance, D is calculated as where R is the cell radius and N is the number of cells per cluster. Cells may vary in radius from 1 to 30 kilometres (0.62 to 18.64 mi). The boundaries of
3737-430: Is not allowed unless under very specific circumstances and under regulatory scrutiny. This has often taken place when a new company is assigned a mobile telephony license (such as Free Italia 's 10-year national roaming deal with Wind Tre ), to create a more competitive market by allowing the new entrant to offer coverage comparable to that of established operators (by requiring the existing operators to allow roaming while
3838-431: Is not easy for an operator to know when a prepaid subscriber has left the network. To free up resources on the network for new customers, an operator will periodically delete prepaid SIM cards which have not been used for some time, at which point, their service (and its associated phone number) is discontinued. The rules for when this deletion happens vary from operator to operator, but may typically occur after six months to
3939-402: Is outside the bounds of the "home network". The legal roaming business aspects negotiated between the roaming partners for billing of the services obtained are usually stipulated in so called roaming agreements. The GSM Association broadly outlines the content of such roaming agreements in standardized form for its members. For the legal aspects of authentication, authorization and billing of
4040-422: Is roaming onto. This is because they can not pass that extra cost onto customers ("free roaming"). Roaming calls within a local tariff area, when at least one of the phones belong outside that area. Usually implemented with trombone routing also known as tromboning . Cellular network A cellular network or mobile network is a telecommunications network where the link to and from end nodes
4141-510: Is routed to an Interactive Voice Response (IVR) device that announces to the user that the account balance is low and suggests they add funds to the account so their service is not interrupted. When the user's account balance is depleted, the service is suspended until they added funds to their account. If the user's account balance is depleted, all call attempts are routed to the IVR. These patents expired in 2010 and 2012 respectively. The prepaid service
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4242-660: Is supported by the Telecommunication processes of mobility management, authentication , authorization and accounting billing procedures (known as AAA or 'triple A'). Roaming is divided into "SIM-based roaming" and "username/password-based roaming", whereby the technical term "roaming" also encompasses roaming between networks of different network standards, e.g. WLAN (Wireless Local Area Network) or GSM (Global System for Mobile Communications) . Device equipment and functionality, such as SIM card capability, antenna and network interfaces , and power management , determine
4343-594: Is typically easiest when using the GSM standard, as it is used by over 80% of the world's mobile operators, and most devices support it. However, even then, there may be problems, since countries have allocated different frequency bands for GSM communications (there are two groups of countries: most GSM countries use 900/1800 MHz, but the United States and some other countries in the Americas have allocated 850/1900 MHz): for
4444-411: Is viable because a given radio frequency can be reused in a different area for an unrelated transmission. In contrast, a single transmitter can only handle one transmission for a given frequency. Inevitably, there is some level of interference from the signal from the other cells which use the same frequency. Consequently, there must be at least one cell gap between cells which reuse the same frequency in
4545-618: The UMTS system where it allows for low downlink latency in packet-based connections. In LTE/4G, the Paging procedure is initiated by the MME when data packets need to be delivered to the UE. Paging types supported by the MME are: In a primitive taxi system, when the taxi moved away from a first tower and closer to a second tower, the taxi driver manually switched from one frequency to another as needed. If communication
4646-575: The Bell System , with cellular assets transferred to the Regional Bell Operating Companies . The wireless revolution began in the early 1990s, leading to the transition from analog to digital networks . The MOSFET invented at Bell Labs between 1955 and 1960, was adapted for cellular networks by the early 1990s, with the wide adoption of power MOSFET , LDMOS ( RF amplifier ), and RF CMOS ( RF circuit ) devices leading to
4747-654: The European Parliament and Commission in May of the same year came into force. It abolished all roaming charges within the EU, Iceland, Liechtenstein and Norway. Countries that do not share a supra-national authority have also begun examining the provision of international roaming services. In April 2011, Singapore and Malaysia announced that they had agreed with operators to reduce voice and SMS rates for roaming between their two countries. In August 2012, Australia and New Zealand published
4848-577: The IREG testing is to test the proper functioning of the established communication links, the TADIG testing is to check the billability of the calls. The usage by a subscriber in a visited network is captured in a file called the TAP (Transferred Account Procedure) for GSM / CIBER (Cellular Intercarrier Billing Exchange Record) for CDMA, AMPS etc... file and is transferred to the home network. A TAP/CIBER file contains details of
4949-688: The U.S., whereas others define it as anywhere within the carrier's network. In the UK, the main network providers generally send text alerts to advise users that they will now be charged international rates so it is clear when this will apply. UK data roaming charges abroad vary depending on the nature of the phone agreement (either pay as you go or monthly contracts ). Some carriers, including T-Mobile and Virgin Mobile , do not allow pay as you go customers to use international roaming without pre-purchase of an international "add on" or "bolt on." An operator intending to provide roaming services to visitors publishes
5050-709: The US, used interchangeably with "mobile phone". However, satellite phones are mobile phones that do not communicate directly with a ground-based cellular tower but may do so indirectly by way of a satellite. There are a number of different digital cellular technologies, including: Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), cdmaOne , CDMA2000 , Evolution-Data Optimized (EV-DO), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Digital Enhanced Cordless Telecommunications (DECT), Digital AMPS (IS-136/TDMA), and Integrated Digital Enhanced Network (iDEN). The transition from existing analog to
5151-468: The ability to move from one mobile operator to another in the same country. For example, a postpaid subscriber of T-Mobile USA who is allowed to roam on AT&T Mobility and/or the regional carriers Viaero Wireless and U.S. Cellular 's networks would have national roaming rights; prepaid providers on the other hand typically only allow a more restricted national roaming ability for cost reasons. For commercial and license reasons, this type of roaming
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#17330860349795252-417: The access possibilities. Using the example of WLAN/GSM roaming, the following scenarios can be differentiated (cf. GSM Association Permanent Reference Document AA.39): Although these user/network scenarios focus on roaming from GSM network operator's networks, clearly roaming can be bi-directional, i.e. from public WLAN operators to GSM networks. Traditional roaming in networks of the same standard, e.g. from
5353-508: The agreement without having to pay their roaming fee. The agreement was signed in April 2019. There are no additional charges, just like in EU's "Roaming like home" project. In November 2021, Cameroon, Central African Republic, Congo, Equatorial Guinea, Chad and Gabon committed to bilateral agreements to lift charges and cut interconnection tariffs. This type refers to the ability of moving from one region to another region inside national coverage of
5454-467: The basis of 3G ). With FDMA, the transmitting and receiving frequencies used by different users in each cell are different from each other. Each cellular call was assigned a pair of frequencies (one for base to mobile, the other for mobile to base) to provide full-duplex operation. The original AMPS systems had 666 channel pairs, 333 each for the CLEC "A" system and ILEC "B" system. The number of channels
5555-499: The calls made by the subscriber viz. location, calling party, called party, time of call and duration, etc. The TAP/CIBER files are rated as per the tariffs charged by the visited operator. The home operator then bills these calls to its subscribers and may charge a mark-up/tax applicable locally. As recently many carriers launched own retail rate plans and bundles for Roaming, TAP records are generally used for wholesale Inter-Operators settlements only Roaming fees are typically charged on
5656-563: The capping of roaming within the EEA, the Commission replaced the law in 2012. Under the 2012 Regulation, retail roaming capping charges expired in 2017 and wholesale capping charges expired in 2022. In mid-2009 there was also an €0.11 (excluding tax) maximum price for SMS text message included into this regulation. On 11 June 2013, the European Commission voted to end mobile roaming charges for
5757-493: The cells can also overlap between adjacent cells and large cells can be divided into smaller cells. The frequency reuse factor is the rate at which the same frequency can be used in the network. It is 1/K (or K according to some books) where K is the number of cells which cannot use the same frequencies for transmission. Common values for the frequency reuse factor are 1/3, 1/4, 1/7, 1/9 and 1/12 (or 3, 4, 7, 9 and 12, depending on notation). In case of N sector antennas on
5858-418: The centers of the cells and were omnidirectional, a cellular map can be redrawn with the cellular telephone towers located at the corners of the hexagons where three cells converge. Each tower has three sets of directional antennas aimed in three different directions with 120 degrees for each cell (totaling 360 degrees) and receiving/transmitting into three different cells at different frequencies. This provides
5959-399: The credits. There is no compulsion on a prepaid mobile phone user to top up their balance. To maintain revenues, some operators have devised reward schemes designed to encourage frequent top-ups. For example, an operator may offer some free SMS to use next month if a user tops up by a certain amount this month. Unlike postpaid phones , where subscribers have to terminate their contracts, it
6060-500: The desired service including mobility management, registration, call set-up, and handover . Any phone connects to the network via an RBS ( Radio Base Station ) at a corner of the corresponding cell which in turn connects to the Mobile switching center (MSC). The MSC provides a connection to the public switched telephone network (PSTN). The link from a phone to the RBS is called an uplink while
6161-615: The development and proliferation of digital wireless mobile networks. The first commercial digital cellular network, the 2G generation, was launched in 1991. This sparked competition in the sector as the new operators challenged the incumbent 1G analog network operators. To distinguish signals from several different transmitters, a number of channel access method s have been developed, including frequency-division multiple access (FDMA, used by analog and D-AMPS systems), time-division multiple access (TDMA, used by GSM ) and code-division multiple access (CDMA, first used for PCS , and
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#17330860349796262-589: The digital standard followed a very different path in Europe and the US . As a consequence, multiple digital standards surfaced in the US, while Europe and many countries converged towards the GSM standard. A simple view of the cellular mobile-radio network consists of the following: This network is the foundation of the GSM system network. There are many functions that are performed by this network in order to make sure customers get
6363-419: The final agreement was signed in late 1997. The announcement was made on January 26, 1998 (or listen to it). Prepaid service enabled carriers in third world countries to add subscribers without having to print monthly statements or having an accounts receivable department, and gave them the ability to add subscribers without concern for their ability to pay their bills. patent holder ). In 1996 MTN became
6464-583: The first mobile operator to introduce a prepaid cellular service in Africa, popularizing "pay as you go" in emerging markets. The first Prepaid card was called "Mimo" and was launched by TMN, the mobile phone operator of Portugal Telecom, in September 1995. In 2006 Swisscom celebrated ten years with its product and service "NATEL® easy" which also holds a patent on "Prepaid mobile subscriber identification card and method implemented thereby". A prepaid plan may have
6565-480: The first time. Following a European Commission vote on 15 December 2016, roaming charges within the European Union were to be abolished by June 2017. While the European Commission (EC) believed that ending roaming charges would stimulate entrepreneurship and trade, mobile operators had their doubts about the changes. On 15 June 2017, Regulation (EU) 2016/2286, nicknamed "Roam like at Home" and having been signed by
6666-470: The following methods: Since July 2013, at least 80 countries globally (including 37 on the African continent) have mandated, or are actively considering mandating, the registration of prepaid SIM users. As of January 2020, researches found that governments of 155 countries have been mandating SIM registration laws; in some countries, prepaid users must submit biometrics like photos and fingerprints. The reason
6767-584: The future. Cell towers frequently use a directional signal to improve reception in higher-traffic areas. In the United States , the Federal Communications Commission (FCC) limits omnidirectional cell tower signals to 100 watts of power. If the tower has directional antennas, the FCC allows the cell operator to emit up to 500 watts of effective radiated power (ERP). Although the original cell towers created an even, omnidirectional signal, were at
6868-501: The idle state (connected to the network, but with no active call). It occurs for example when a call is made to a roaming cell phone. Signaling process: In order that a subscriber is able to register on to a visited network, a roaming agreement needs to be in place between the visited network and the home network. This agreement is established after a series of testing processes called IREG (International Roaming Expert Group) and TADIG (Transferred Account Data Interchange Group). While
6969-477: The increasing popularity and availability of "free roaming" service plan, where there is no cost difference between on and off network usage. The benefits of getting service from a mobile phone operator, that is not local to a user, can include cheaper rates, or features and phones that are not available on their local mobile phone operator, or to get to a particular mobile phone operator's network to get free calls to other customers of that mobile phone operator through
7070-499: The metropolitan area of Tokyo . Within five years, the NTT network had been expanded to cover the whole population of Japan and became the first nationwide 1G network. It was an analog wireless network . The Bell System had developed cellular technology since 1947, and had cellular networks in operation in Chicago and Dallas prior to 1979, but commercial service was delayed by the breakup of
7171-458: The mobile operator ("internal roaming"). Initially, operators may have provided commercial offers restricted to a region (sometimes to a town). Due to the success of GSM and the decrease in cost, regional roaming is rarely offered to clients except in nations with wide geographic areas like the US, Russia, India, etc., in which there are a number of regional operators. In Russia even country-wide operators charge different tariffs depending on whether
7272-410: The most important use of broadcast information is to set up channels for one-to-one communication between the mobile transceiver and the base station. This is called paging . The three different paging procedures generally adopted are sequential, parallel and selective paging. The details of the process of paging vary somewhat from network to network, but normally we know a limited number of cells where
7373-454: The name. A number of the standards making industry bodies have come together to define and achieve interoperability between the technologies as a means to achieve inter-standards roaming. This is currently an ongoing effort. Mobile signature roaming allows an access point to get a mobile signature from any end-user, even if the AP and the end-user have not contracted a commercial relationship with
7474-472: The network, via base stations, even if some of the devices are moving through more than one cell during transmission. The design of cellular networks allows for seamless handover , enabling uninterrupted communication when a device moves from one cell to another. Modern cellular networks utilize advanced technologies such as Multiple Input Multiple Output (MIMO), beamforming , and small cells to enhance network capacity and efficiency. Cellular networks offer
7575-422: The new entrant has time to build up its own network), or where mobile network infrastructure has been destroyed by natural or man-made means, such as during the 2022 Russian invasion of Ukraine where Ukrainian mobile operators had to quickly implement national roaming with each other to compensate for network infrastructure destroyed in said invasion. In a country like India, where the number of regional operators
7676-536: The number of subscribers per cell site, greater data throughput per user, or some combination thereof. Quadrature Amplitude Modulation (QAM) modems offer an increasing number of bits per symbol, allowing more users per megahertz of bandwidth (and decibels of SNR), greater data throughput per user, or some combination thereof. The key characteristic of a cellular network is the ability to reuse frequencies to increase both coverage and capacity. As described above, adjacent cells must use different frequencies, however, there
7777-506: The other way is termed downlink . Radio channels effectively use the transmission medium through the use of the following multiplexing and access schemes: frequency-division multiple access (FDMA), time-division multiple access (TDMA), code-division multiple access (CDMA), and space-division multiple access (SDMA). Small cells, which have a smaller coverage area than base stations, are categorised as follows: Prepaid mobile phone A prepaid mobile device , also known as
7878-501: The phone is located (this group of cells is called a Location Area in the GSM or UMTS system, or Routing Area if a data packet session is involved; in LTE , cells are grouped into Tracking Areas). Paging takes place by sending the broadcast message to all of those cells. Paging messages can be used for information transfer. This happens in pagers , in CDMA systems for sending SMS messages, and in
7979-480: The phone, or it does not). Some operators (e.g., Orange ) allow their pre-paid customers to have a small negative balance to allow short calls or texts when the customer's credit has been completely used. This is then deducted when the customer next adds more credit. The time most likely for a prepaid customer to switch to a different service provider is when the prepaid account reaches a "zero credit balance". Like other service providers, mobile service providers losing
8080-478: The prepaid balance amount until no funds remain (at which time services stop functioning). A user may avoid interruptions in service by making payments to increase the remaining balance. Methods of payment: Credit purchased for a prepaid mobile phone may have a time limit – for example, 120 days from the date the last credit was added. In these cases, customers who do not add more credit before expiration will have their remaining balance depleted through expiration of
8181-670: The prepaid service, by offering a "pay monthly" contract. Prepaid phones and SIMs in the United Kingdom are known as "Pay as you go". Usage of prepaid cellphone service was common in most parts of the world. In 2012 around 70% of customers in Western Europe and China use prepaid phones with the figure rising to over 90% for customers in India and Africa. 36% of cellphone users in the United States of America were using some form of prepaid service as of 2021. Prepaid SIM cards are also becoming
8282-414: The prevention, investigation and/or prosecution of associated crimes. As a result, policymakers decided to repeal the regulation three years later. A prepaid phone number specifically purchased to be used briefly and then replaced is known colloquially as a burner phone or burner . A Los Angeles technology company developed a mobile application of the same name that replicates this functionality for
8383-483: The receiving end to produce a somewhat normal-sounding voice at the receiver. TDMA must introduce latency (time delay) into the audio signal. As long as the latency time is short enough that the delayed audio is not heard as an echo, it is not problematic. TDMA is a familiar technology for telephone companies, which used time-division multiplexing to add channels to their point-to-point wireline plants before packet switching rendered FDM obsolete. The principle of CDMA
8484-568: The recommendations of the final report. On 19 February 2020, Bolivia , Colombia , Ecuador and Peru voted, through the auspice of the Andean Community , to eliminate roaming fees amongst themselves. The agreement is set to start in 2022. On 1 July 2021, Serbia , Albania , Montenegro , Bosnia & Herzegovina , North Macedonia and Kosovo abolished roaming fees as part of Mini Schengen project, allowing SIM holders on those countries to use their domestic packages on another country in
8585-405: The requirements of that mobile phone operator, they will be denied service. In order to permanently roam customers may use a false address and online billing , or a relative or friend's address which is in the required area, and a 3rd party billing option. Most mobile phone operators discourage or prohibit permanent roaming since they must pay per minute rates to the network operator their customer
8686-450: The results of deficiencies in the prepaid systems used by the wireless carriers, as technology has evolved to the point where these are easily managed by triggers or APIs to third-party solution providers. Current models being deployed by wireless carriers are capable of setting the price points for all services on an individual basis (via packages), such that higher pricing is a marketing decision. As described above, prepaid accounts require
8787-442: The same MSSP . Otherwise, an AP would have to build commercial terms with as many MSSPs as possible, and this might be a cost burden. This means that a mobile signature transaction issued by an Application Provider should be able to reach the appropriate MSSP, and this should be transparent for the AP. Network elements belonging to the same Operator but located in different areas (a typical situation where assignment of local licenses
8888-415: The same base station site, each with different direction, the base station site can serve N different sectors. N is typically 3. A reuse pattern of N/K denotes a further division in frequency among N sector antennas per site. Some current and historical reuse patterns are 3/7 (North American AMPS), 6/4 (Motorola NAMPS), and 3/4 ( GSM ). If the total available bandwidth is B , each cell can only use
8989-472: The same frequencies are not reused in adjacent cells, which would cause co-channel interference . The increased capacity in a cellular network, compared with a network with a single transmitter, comes from the mobile communication switching system developed by Amos Joel of Bell Labs that permitted multiple callers in a given area to use the same frequency by switching calls to the nearest available cellular tower having that frequency available. This strategy
9090-458: The same frequencies, and the different base stations and users are separated by codes rather than frequencies. While N is shown as 1 in this example, that does not mean the CDMA cell has only one sector, but rather that the entire cell bandwidth is also available to each sector individually. Recently also orthogonal frequency-division multiple access based systems such as LTE are being deployed with
9191-406: The tariffs that would be charged in their network at least sixty days prior to its implementation under normal situations. The visited operator tariffs may include tax, discounts etc. and would be based on duration in case of voice calls. For data calls, the charging may be based on the data volume sent and received. Some operators also charge a separate fee for call setup i.e. for the establishment of
9292-548: The terrain, and the frequency band being used. A cell typically uses a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed service quality within each cell. When joined together, these cells provide radio coverage over a wide geographic area. This enables numerous devices , including mobile phones , tablets , laptops equipped with mobile broadband modems , and wearable devices such as smartwatches , to communicate with each other and with fixed transceivers and telephones anywhere in
9393-442: The use of mobile networks outside its original country can lead to significant billing by its original mobile data operator without an addon to their current phone service. This type refers to roaming between two standards. This term is now widely used in mobile communications where especially CDMA customers want to use their phone in areas where there is no CDMA network or there is no roaming agreement in place to support roaming on
9494-661: The used standard. In Europe there are hardly any CDMA networks. Most CDMA customers originate from the Americas or the Far East. In order to enable them to roam in Europe inter-standard roaming is the solution. The CDMA customers arriving in Europe can register on the available GSM networks. Since mobile communication technologies have evolved independently across continents, there is significant challenge in achieving seamless roaming across these technologies. Typically, these technologies were implemented in accordance with technological standards laid down by different industry bodies and hence
9595-473: The users are within or outside of their "home region". A number of legislative attempts to remove the "internal roaming" failed due to opposition from operators. Following the annexation of Crimea in 2014 the Russian operators are facing significant criticism as they do not offer their services inside Crimea directly, even though formally it's recognized as a regular federal subject inside Russia. This type refers to
9696-400: The visiting subscriber, the roaming agreements typically can comprise minimal safety standards, as e.g. location update procedures or financial security or warranty procedures. The details of the roaming process differ among types of cellular networks, but in general, the process resembles the following: Location updating is the mechanism that is used to determine the location of an MS in
9797-622: Was expanded to 416 pairs per carrier, but ultimately the number of RF channels limits the number of calls that a cell site could handle. FDMA is a familiar technology to telephone companies, which used frequency-division multiplexing to add channels to their point-to-point wireline plants before time-division multiplexing rendered FDM obsolete. With TDMA, the transmitting and receiving time slots used by different users in each cell are different from each other. TDMA typically uses digital signaling to store and forward bursts of voice data that are fit into time slices for transmission, and expanded at
9898-438: Was interrupted due to a loss of a signal, the taxi driver asked the base station operator to repeat the message on a different frequency. In a cellular system, as the distributed mobile transceivers move from cell to cell during an ongoing continuous communication, switching from one cell frequency to a different cell frequency is done electronically without interruption and without a base station operator or manual switching. This
9999-409: Was invented by Subscriber Computing, Inc., an Orange County company, (1986–1998), founded and directed by Arlene Harris . The patents covering this invention are: These patents describe the ability to access the cost of a call and deduct the cost of the call from the user's account balance in near real time. If the user's balance is below the carrier-defined threshold, the next call that the user makes
10100-471: Was not developed by Bell Labs ), CDMA has scaled well to become the basis for 3G cellular radio systems. Other available methods of multiplexing such as MIMO , a more sophisticated version of antenna diversity , combined with active beamforming provides much greater spatial multiplexing ability compared to original AMPS cells, that typically only addressed one to three unique spaces. Massive MIMO deployment allows much greater channel reuse, thus increasing
10201-625: Was sold to Metro Mobile in June 1989, and was implemented in November 1989. The prepaid service was also sold to carriers in Mexico; Celcom in 1994, and implementation took place in Monterrey, and to Telcel, where implementation began in November 1997 and production took place beginning in April 1998. Ericsson also became a partner in the prepaid service; a Memorandum of Understanding (MOU) was signed in June 1997 and
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