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A mobile phone (also called mobile, cellular telephone, or cell phone) is an electronic device used for two-way radio telecommunication over a cellular network of base stations known as cell sites. Mobile phones differ from cordless telephones, which only offer telephone service within limited range through a single base station attached to a fixed land line, for example within a home or an office.

A mobile phone allows its user to make and receive telephone calls to and from the public telephone network which includes other mobiles and fixed-line phones across the world. It does this by connecting to a cellular network owned by a mobile network operator. A key feature of the cellular network is that it enables seamless telephone calls even when the user is moving around wide areas via a process known as handoff or handover.

In addition to being a telephone, modern mobile phones also support many additional services, and accessories, such as SMS (or text) messages, e-mail, Internet access, gaming, Bluetooth and infrared short range wireless communication, camera, MMS messaging, MP3 player, radio and GPS. Low-end mobile phones are often referred to as feature phones, whereas high-end mobile phones that offer more advanced computing ability are referred to as smartphones.

The first handheld mobile phone was demonstrated by Dr. Martin Cooper of Motorola in 1973, using a handset weighing 2 kg (4.4 lb).[1] Motorola released the first commercially available mobile phone, the DynaTAC 8000x, in 1983. In the year 1990, 12.4 million people worldwide had cellular subscriptions.[2] By the end of 2009, less than 20 years later, the number of mobile cellular subscriptions worldwide reached approximately 4.6 billion, 370 times the 1990 number, penetrating the developing economies and reaching the bottom of the economic pyramid.[3]

Contents

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History

An evolution of mobile phones

Radiophones have a long and varied history going back to Reginald Fessenden's invention and shore-to-ship demonstration of radio telephony, through the Second World War with military use of radio telephony links and civil services in the 1950s.

The first mobile telephone call made from a car occurred in St. Louis, Missouri, USA on June 17, 1946, using the Bell System's Mobile Telephone Service, but the system was impractical from what is considered a portable handset today. The equipment weighed 80 lbs, and the AT&T service, basically a massive party line, cost $30 USD per month (equal to $337.33 today) plus 30 to 40 cents per local call, equal to $3.37 to $4.5 today.[4]

In 1960, the world’s first partly automatic car phone system, Mobile System A (MTA), was launched in Sweden. MTA phones were composed of vacuum tubes and relays, and had a weight of 40 kg. In 1962, a more modern version called Mobile System B (MTB) was launched, which was a push-button telephone, and which used transistors in order to enhance the telephone’s calling capacity and improve its operational reliability. In 1971, the MTD version was launched, opening for several different brands of equipment and gaining commercial success.[5][6]

Martin Cooper, a Motorola researcher and executive is considered to be the inventor of the first practical mobile phone for handheld use in a non-vehicle setting, after a long race against Bell Labs for the first portable mobile phone. Using a modern, if somewhat heavy portable handset, Cooper made the first call on a handheld mobile phone on April 3, 1973 to his rival, Dr. Joel S. Engel of Bell Labs.[7]

The first commercially automated cellular network (the 1G generation) was launched in Japan by NTT in 1979, initially in 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. In 1981, this was followed by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway and Sweden.[8] NMT was the first mobile phone network featuring international roaming. The first 1G network launched in the USA was Chicago-based Ameritech in 1983 using the Motorola DynaTAC mobile phone. Several countries then followed in the early-to-mid 1980s including the UK, Mexico and Canada.

The first "modern" network technology on digital 2G (second generation) cellular technology was launched by Radiolinja (now part of Elisa Group) in 1991 in Finland on the GSM standard, which also marked the introduction of competition in mobile telecoms when Radiolinja challenged incumbent Telecom Finland (now part of TeliaSonera) who ran a 1G NMT network.

In 2001, the first commercial launch of 3G (Third Generation) was again in Japan by NTT DoCoMo on the WCDMA standard.[9]

One of the newest 3G technologies to be implemented is High-Speed Downlink Packet Access (HSDPA). It is an enhanced 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access (HSPA) family, also coined 3.5G, 3G+ or turbo 3G, which allows networks based on Universal Mobile Telecommunications System (UMTS) to have higher data transfer speeds and capacity.

Features

All mobile phones have a number of features in common, but manufacturers also try to differentiate their own products by implementing additional functions to make them more attractive to consumers. This has led to great innovation in mobile phone development over the last 20 years.

The common components found on all phones are:

  • A rechargeable battery providing the power source for the phone functions
  • An input mechanism and display to allow the user to interact with the phone. The most common input mechanism is a keypad, but touch screens are also found in some high-end smartphones.
  • Basic mobile phone services to allow users to make calls and send text messages.
  • All GSM phones use a SIM card to allow an account to be swapped among devices. Some CDMA devices also have a similar card called a R-UIM.
  • Individual GSM, WCDMA, iDEN and some satellite phone devices are uniquely identified by an International Mobile Equipment Identity (IMEI) number.

Low-end mobile phones are often referred to as feature phones, and offer basic telephony, as well as functions such as playing music and taking photos, and sometimes simple applications based on generic managed platforms such as Java ME or BREW. Handsets with more advanced computing ability through the use of native software applications became known as smartphones. The first smartphone was the Nokia 9000 Communicator in 1996 which added PDA functionality to the basic mobile phone at the time. As miniaturization and increased processing power of microchips has enabled ever more features to be added to phones, the concept of the smartphone has evolved, and what was a high-end smartphone five years ago, is a standard phone today.

Several phone series have been introduced to address a given market segment, such as the RIM BlackBerry focusing on enterprise/corporate customer email needs; the SonyEricsson Walkman series of musicphones and Cybershot series of cameraphones; the Nokia Nseries of multimedia phones, the Palm Pre the HTC Dream and the Apple iPhone.

Other features that may be found on mobile phones include GPS navigation, music (MP3) and video (MP4) playback, RDS radio receiver, alarms, memo recording, personal digital assistant functions, ability to watch streaming video, video download, video calling, built-in cameras (1.0+ Mpx) and camcorders (video recording), with autofocus and flash, ringtones, games, PTT, memory card reader (SD), USB (2.0), dual line support, infrared, Bluetooth (2.0) and WiFi connectivity, instant messaging, Internet e-mail and browsing and serving as a wireless modem. Nokia and the University of Cambridge demonstrated a bendable cell phone called the Morph.[10]

Software and applications

A Toshiba TG01 phone with touchscreen feature

The most commonly used data application on mobile phones is SMS text messaging. The first SMS text message was sent from a computer to a mobile phone in 1992 in the UK, while the first person-to-person SMS from phone to phone was sent in Finland in 1993.

Other non-SMS data services used on mobile phones include mobile music, downloadable logos and pictures, gaming, gambling, adult entertainment and advertising. The first downloadable mobile content was sold to a mobile phone in Finland in 1998, when Radiolinja (now Elisa) introduced the downloadable ringtone service. In 1999, Japanese mobile operator NTT DoCoMo introduced its mobile Internet service, i-Mode, which today is the world's largest mobile Internet service.

The first mobile news service, delivered via SMS, was launched in Finland in 2000. Mobile news services are expanding with many organisations providing "on-demand" news services by SMS. Some also provide "instant" news pushed out by SMS.

Mobile payments were first trialled in Finland in 1998 when two Coca-Cola vending machines in Espoo were enabled to work with SMS payments. Eventually, the idea spread and in 1999 the Philippines launched the first commercial mobile payments systems, on the mobile operators Globe and Smart. Today, mobile payments ranging from mobile banking to mobile credit cards to mobile commerce are very widely used in Asia and Africa, and in selected European markets.

Power supply

Mobile phone charging service in Uganda

Mobile phones generally obtain power from rechargeable batteries. There are a variety of ways used to charge cell phones, including USB, portable batteries, mains power (using an AC adapter), cigarette lighters (using an adapter), or a dynamo. In 2009, the first wireless charger was released for consumer use.[11]

Standardization of Micro-USB connector for charging

Starting from 2010, many mobile phone manufacturers have agreed to use the Micro-USB connector for charging their phones.[12] The mobile phone manufacturers who have agreed to this standard include:

  • LG
  • Motorola
  • Nokia
  • Research In Motion
  • Samsung
  • Sony Ericsson

On 17 February 2009, the GSM Association announced[13] that they had agreed on a standard charger for mobile phones. The standard connector to be adopted by 17 manufacturers in the Open Mobile Terminal Platform including Nokia, Motorola and Samsung is to be the micro-USB connector (several media reports erroneously reported this as the mini-USB). The new chargers will be much more efficient than existing chargers. Having a standard charger for all phones, means that manufacturers will no longer have to supply a charger with every new phone.

In addition, on 22 October 2009, the International Telecommunication Union (ITU) announced that it had embraced micro-USB as the Universal Charger Solution its "energy-efficient one-charger-fits-all new mobile phone solution," and added: "Based on the Micro-USB interface, UCS chargers will also include a 4-star or higher efficiency rating — up to three times more energy-efficient than an unrated charger."[14]

Charger efficiency

The world's five largest handset makers introduced a new rating system in November 2008 to help consumers more easily identify the most energy-efficient chargers

The majority of energy lost in a mobile phone charger is in its no load condition, when the mobile phone is not connected but the charger has been left plugged in and using power. To combat this, in November 2008, the top five mobile phone manufacturers Nokia, Samsung, LG Electronics, Sony Ericsson, and Motorola set up a star rating system to rate the efficiency of their chargers in the no-load condition. Starting at zero stars for >0.5 W and going up to the top five star rating for <0.03 W (30 mW) no load power.[15]

A number of semiconductor companies offering flyback controllers, such as Power Integrations and CamSemi, now claim that the five-star standard can be achieved with use of their product.[16]

Battery

Formerly, the most common form of mobile phone batteries were nickel metal-hydride, as they have a low size and weight. Lithium ion batteries are sometimes used, as they are lighter and do not have the voltage depression that nickel metal-hydride batteries do. Many mobile phone manufacturers have now switched to using lithium-polymer batteries as opposed to the older Lithium-Ion, the main advantages of this being even lower weight and the possibility to make the battery a shape other than strict cuboid.[17] Mobile phone manufacturers have been experimenting with alternative power sources, including solar cells.

SIM card

Typical mobile phone SIM card

GSM mobile phones require a small microchip called a Subscriber Identity Module or SIM Card, to function. The SIM card is approximately the size of a small postage stamp and is usually placed underneath the battery in the rear of the unit. The SIM securely stores the service-subscriber key (IMSI) used to identify a subscriber on mobile telephony devices (such as mobile phones and computers). The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device.

A SIM card contains its unique serial number, internationally unique number of the mobile user (IMSI), security authentication and ciphering information, temporary information related to the local network, a list of the services the user has access to and two passwords (PIN for usual use and PUK for unlocking).

SIM cards are available in three standard sizes. The first is the size of a credit card (85.60 mm × 53.98 mm x 0.76 mm). The newer, most popular miniature version has the same thickness but a length of 25 mm and a width of 15 mm, and has one of its corners truncated (chamfered) to prevent misinsertion. The newest incarnation known as the 3FF or micro-SIM has dimensions of 15 mm × 12 mm. Most cards of the two smaller sizes are supplied as a full-sized card with the smaller card held in place by a few plastic links; it can easily be broken off to be used in a device that uses the smaller SIM.

The first SIM card was made in 1991 by Munich smart card maker Giesecke & Devrient for the Finnish wireless network operator Radiolinja. Giesecke & Devrient sold the first 300 SIM cards to Elisa (ex. Radiolinja).

Those cell phones that do not use a SIM Card have the data programmed in to their memory. This data is accessed by using a special digit sequence to access the "NAM" as in "Name" or number programming menu. From there, information can be added, including a new number for the phone, new Service Provider numbers, new emergency numbers, new Authentication Key or A-Key code, and a Preferred Roaming List or PRL. However, to prevent the phone being accidentally disabled or removed from the network, the Service Provider typically locks this data with a Master Subsidiary Lock (MSL). The MSL also locks the device to a particular carrier when it is sold as a loss leader.

The MSL applies to the SIM only so once the contract has been completed the MSL still applies to the SIM. The phone, however, is also initially locked by the manufacturer into the Service Provider's MSL. This lock may be disabled so that the phone can use other Service Providers' SIM cards. Most phones purchased outside the U.S. are unlocked phones because there are numerous Service Providers close to one another or have overlapping coverage. The cost to unlock a phone varies but is usually very cheap and is sometimes provided by independent phone vendors.

A similar module called a Removable User Identity Module or RUIM card is present in some CDMA networks, notably in China and Indonesia.

Multi-card hybrid phones

A hybrid mobile phone can take more than one SIM card, even of different types. The SIM and RUIM cards can be mixed together, and some phones also support three or four SIMs[18][19]

They are popular in India and Indonesia, attributed to lower on-net call rates.

3D mobile phone

Spice Mobile has launched Spice View M-67 3D Dual-SIM Mobile Phone. India's first 3D mobile phone allowing us to view 3D pictures and videos along with phone's user interface without 3D glasses. The phone is equipped with 2 megapixel camera, but only takes 2D.[20]

Mobile phones in society

Market share

Mobile phone subscribers per 100 inhabitants 1997–2007

The world's largest individual mobile operator is China Mobile with over 500 million mobile phone subscribers.[21] The world's largest mobile operator group by subscribers is UK-based Vodafone[citation needed]. There are over 600 mobile operators and carriers in commercial production worldwide[citation needed]. Over 50 mobile operators have over 10 million subscribers each, and over 150 mobile operators have at least one million subscribers by the end of 2009 (source wireless intelligence).

Source Date Nokia SAMSUNG LG Apple RIM Sony Ericsson Others References
IDC Q1/2010 36.6% 21.8% 9.2%
3.6% 3.6% 25.3% [22]
Gartner Q1/2010 35.0% 20.6% 8.6%
3.4% 3.1% 29.3% [23]
Gartner Q3/2010 33.8% 21.8% 8.7% 4.3% 3.8%
27.6% [24]

Note: At Q1/2010 IDC and Gartner represent the same ranking order and at Q3 2010 Sony Ericsson is not in the top 5 list.

Competitive forces emerged in the Asia Pacific (excluding Japan) region at Q3 2010 to the detriment of market leader Nokia. Brands such as Micromax, Nexian, and i-Mobile chipped away at Nokia's market share plus Android powered smartphones also gained momentum across the region at the cost of Nokia.

Other manufacturers include Apple Inc., Audiovox (now UTStarcom), CECT, HTC Corporation, Fujitsu, Kyocera, Mitsubishi Electric, NEC, Panasonic, Palm, Matsushita, Pantech Wireless Inc., Philips, Qualcomm Inc., Research In Motion Ltd. (RIM), Sagem, Sanyo, Sharp, Sierra Wireless, SK Teletech, T&A Alcatel, Huawei, Trium, Toshiba and Vidalco. There are also specialist communication systems related to (but distinct from) mobile phones.

Media

In 1998, one of the first examples of selling media content through the mobile phone was the sale of ringtones by Radiolinja in Finland. Soon afterwards, other media content appeared such as news, videogames, jokes, horoscopes, TV content and advertising. Most early content for mobile tended to be copies of legacy media, such as the banner advertisement or the TV news highlight video clip. Recently, unique content for mobile has been emerging, from the ringing tones and ringback tones in music to "mobisodes," video content that has been produced exclusively for mobile phones.

In 2006, the total value of mobile-phone-paid media content exceeded Internet-paid media content and was worth 31 billion dollars (source Informa 2007). The value of music on phones was worth 9.3 billion dollars in 2007 and gaming was worth over 5 billion dollars in 2007.[25]

The advent of media on the mobile phone has also produced the opportunity to identify and track Alpha Users or Hubs, the most influential members of any social community. AMF Ventures measured in 2007 the relative accuracy of three mass media, and found that audience measures on mobile were nine times more accurate than on the Internet and 90 times more accurate than on TV.[original research?]

The mobile phone is often called the Fourth Screen (if counting cinema, TV and PC screens as the first three) or Third Screen (counting only TV and PC screens).[weasel words] It is also called the Seventh of the Mass Media (with Print, Recordings, Cinema, Radio, TV and Internet the first six).

Usage

Examples

Mobile phones are used for a variety of purposes, including keeping in touch with family members, conducting business, and having access to a telephone in the event of an emergency. Some people carry more than one cell phone for different purposes, such as for business and personal use. Multiple SIM cards may also be used to take advantage of the benefits of different calling plans—a particular plan might provide cheaper local calls, long-distance calls, international calls, or roaming. A study by Motorola found that one in ten cell phone subscribers have a second phone that often is kept secret from other family members. These phones may be used to engage in activities including extramarital affairs or clandestine business dealings.[26] The mobile phone has also been used in a variety of diverse contexts in society, for example:

  • Organizations that aid victims of domestic violence may offer a cell phone to potential victims without the abuser's knowledge. These devices are often old phones that are donated and refurbished to meet the victim's emergency needs.[27]
  • Child predators have taken advantage of cell phones to communicate secretly with children without the knowledge of their parents or teachers.[28]
  • The advent of widespread text messaging has resulted in the cell phone novel; the first literary genre to emerge from the cellular age via text messaging to a website that collects the novels as a whole.[29] Paul Levinson, in Information on the Move (2004), says "...nowadays, a writer can write just about as easily, anywhere, as a reader can read" and they are "not only personal but portable."
  • Mobile telephony also facilitates activism and public journalism being explored by Reuters and Yahoo![30] and small independent news companies such as Jasmine News in Sri Lanka.
  • Mobile phones help lift poor out of poverty. The United Nations report that mobile phones—spreading faster than any other information technology—can improve the livehoods of the poorest people in developing countries. The economic benefits of mobile phones are go well beyond access to information where fixed-line or Internet are not yet available in rural areas, mostly in Least Developed Countries. Mobile phones have spawned a wealth of micro-enterprises, offering work to people with little education and few resources, such as selling airtime on the streets and repair or refurbishing handsets.[31]
  • In Mali and some of African countries, villagers sometimes had to go from village to village all day, covering up to 20 villages, to let friends and relatives know about a wedding, a birth or a death - but it is no longer necessary anymore since signal of mobile phone cover them. Like many African countries, the coverage has better than landline networks, and most people own a mobile phone. However, small villages has no electricity, leaving mobile phone owners to have to charge their phone batteries with accu from motorcycle.[32]

Sharing

In some parts of the world, mobile phone sharing is common. It is prevalent in urban India, as families and groups of friends often share one or more mobiles among their members. There are obvious economic benefits, but often familial customs and traditional gender roles play a part.[33] For example, in Burkina Faso, it is not uncommon for a village to have access to only one mobile phone. The phone is typically owned by a person who is not natively from the village, such as a teacher or missionary, but it is the expected that other members of the village are allowed to use the cell phone to make necessary calls.[34]

Restrictions

There exists a community that believes mobile phone use represents a long-term health risk, although this is currently disputed by the World Health Organization, with forthcoming mobile phone usage recommendations in 2010.[35] Certain countries, including France, have warned against the use of cell phones especially by minors due to health risk uncertainties.[36] Groups of scientists, such as the U.S.-based group Bioinitiative, argue that because mobile phone use is recently introduced technology, long-term "proof" has been impossible and that use should be restricted, or monitored closely, while the technology is still new.

Use while driving

Mobile phone use while driving is common but controversial. Being distracted while operating a motor vehicle has been shown to increase the risk of accident. Because of this, many jurisdictions prohibit the use of mobile phones while driving. Egypt, Israel, Japan, Portugal and Singapore ban both handheld and hands-free use of a mobile phone whilst many other countries –including the UK, France, and many U.S. states– ban handheld phone use only, allowing hands-free use.

Due to the increasing complexity of mobile phones –often more like mobile computers in their available uses– it has introduced additional difficulties for law enforcement officials in being able to tell one usage from another as drivers use their devices. This is more apparent in those countries who ban both handheld and hands-free usage, rather those who have banned handheld use only, as officials cannot easily tell which function of the mobile phone is being used simply by visually looking at the driver. This can mean that drivers may be stopped for using their device illegally on a phone call when, in fact, they were not; instead using the device for a legal purpose such as the phone's incorporated controls for car stereo or satnav usage – either as part of the cars' own device or directly on the mobile phone itself.
Cases like these can often only be proved otherwise by a check of the mobile operators phone call records to see if a call was taking place during the journey concerned. Although, in many countries, the law enforcement official may have stopped the driver for a differing offence, for example, for lack of due care and attention in relation to their driving.

Schools

Some schools limit or restrict the use of mobile phones. Schools set restrictions on the use of mobile phones because of the use of cell phones for cheating on tests, harassment and bullying, causing threats to the schools security, distractions to the students and facilitating gossip and other social activity in school. Many mobile phones are banned in school locker room facilities, public restrooms and swimming pools due to the built-in cameras that most phones now feature.

A recently published study has reviewed the incidence of mobile phone use while cycling and its effects on behaviour and safety.[37]

Privacy

Cell phones have numerous privacy issues.

Governments, law enforcement and intelligence services use mobiles to perform surveillance in the UK and the U.S. They possess technology to activate the microphones in cell phones remotely in order to listen to conversations that take place near to the person who holds the phone.[38][39]

Mobile phones are also commonly used to collect location data. While the phone is turned on, the geographical location of a mobile phone can be determined easily (whether it is being used or not), using a technique known multilateration to calculate the differences in time for a signal to travel from the cell phone to each of several cell towers near the owner of the phone.[40][41]

Health effects

The effect mobile phone radiation has on human health is the subject of recent interest and study, as a result of the enormous increase in mobile phone usage throughout the world (as of June 2009, there were more than 4.3 billion users worldwide[42]). Mobile phones use electromagnetic radiation in the microwave range, which some believe may be harmful to human health. A large body of research exists, both epidemiological and experimental, in non-human animals and in humans, of which the majority shows no definite causative relationship between exposure to mobile phones and harmful biological effects in humans. This is often paraphrased simply as the balance of evidence showing no harm to humans from mobile phones, although a significant number of individual studies do suggest such a relationship, or are inconclusive. Other digital wireless systems, such as data communication networks, produce similar radiation.

The World Health Organization, based upon the majority view of scientific and medical communities, has stated that cancer is unlikely to be caused by cellular phones or their base stations and that reviews have found no convincing evidence for other health effects.[43][44] The WHO expects to make recommendations about mobile phones in 2010.[45] Some national radiation advisory authorities[46] have recommended measures to minimize exposure to their citizens as a precautionary approach.

At least some recent studies, however, have found an association between cell phone use and certain kinds of brain and salivary gland tumors. Lennart Hardell and other authors of a 2009 meta-analysis of 11 studies from peer-reviewed journals concluded that cell phone usage for at least ten years “approximately doubles the risk of being diagnosed with a brain tumor on the same ("ipsilateral") side of the head as that preferred for cell phone use.”[47]

Environmental effects

The ubiquitousness and rapid technological change has led to mobile phones becoming a component of the waste stream. Electronic waste such as mobile phones contain materials that are toxic when they enter into ecosystems and recycling is now carried out to some extent.

Future evolution: Broadband Fourth generation (4G)

The recently released 4th generation, also known as Beyond 3G, aims to provide broadband wireless access with nominal data rates of 100 Mbit/s to fast moving devices, and 1 Gbit/s to stationary devices defined by the ITU-R[48] 4G systems may be based on the 3GPP LTE (Long Term Evolution) cellular standard, offering peak bit rates of 326.4 Mbit/s. It may perhaps also be based on WiMax or Flash-OFDM wireless metropolitan area network technologies that promise broadband wireless access with speeds that reaches 233 Mbit/s for mobile users. The radio interface in these systems is based on all-IP packet switching, MIMO diversity, multi-carrier modulation schemes, Dynamic Channel Assignment (DCA) and channel-dependent scheduling. A 4G system should be a complete replacement for current network infrastructure and is expected to be able to provide a comprehensive and secure IP solution where voice, data, and streamed multimedia can be given to users on a "Anytime, Anywhere" basis, and at much higher data rates than previous generations. Sprint in the US has claimed its WiMax network to be "4G network" which most cellular telecoms standardization experts dispute repeatedly around the world. Sprint's 4G is seen as a marketing gimmick as WiMax itself is part of the 3G air interface. The officially accepted, ITU ratified standards-based 4G networks are not expected to be commercially launched until 2011.

Comparison to similar systems

Car phone 
A type of telephone permanently mounted in a vehicle, these often have more powerful transmitters, an external antenna and loudspeaker for hands free use. They usually connect to the same networks as regular mobile phones.
Cordless telephone (portable phone) 
Cordless phones are telephones which use one or more radio handsets in place of a wired handset. The handsets connect wirelessly to a base station, which in turn connects to a conventional land line for calling. Unlike mobile phones, cordless phones use private base stations (belonging to the land-line subscriber), which are not shared.
Professional Mobile Radio 
Advanced professional mobile radio systems can be very similar to mobile phone systems. Notably, the IDEN standard has been used as both a private trunked radio system as well as the technology for several large public providers. Similar attempts have even been made to use TETRA, the European digital PMR standard, to implement public mobile networks.
Radio phone 
This is a term which covers radios which could connect into the telephone network. These phones may not be mobile; for example, they may require a mains power supply, or they may require the assistance of a human operator to set up a PSTN phone call.
Satellite phone 
This type of phone communicates directly with an artificial satellite, which in turn relays calls to a base station or another satellite phone. A single satellite can provide coverage to a much greater area than terrestrial base stations. Since satellite phones are costly, their use is typically limited to people in remote areas where no mobile phone coverage exists, such as mountain climbers, mariners in the open sea, and news reporters at disaster sites.
IP Phone 
This type of phone delivers or receives calls over internet, LAN or WAN networks using VoIP as opposed to traditional CDMA and GSM networks. In business, the majority of these IP Phones tend to be connected via wired Ethernet, however wireless varieties do exist. Several vendors have developed standalone WiFi phones. Additionally, some cellular mobile phones include the ability to place VoIP calls over cellular high speed data networks and/or wireless internet.[49]

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