The mobile phone (also called a wireless phone or cellular phone) is a short-range, portable electronic device used for mobile voice or data
communication over a network of specialized base stations known as cell sites. In addition to the standard voice function of a telephone,
current mobile phones may support many additional services, and accessories, such as SMS for text messaging, email, packet switching for
access to the Internet, gaming, bluetooth, infrared, camera with video recorder and MMS for sending and receiving photos and video. Most
current mobile phones connect to a cellular network of base stations (cell sites), which is in turn interconnected to the public switched
telephone network (PSTN) (the exception is satellite phones).
According to internal memos, American Telephone & Telegraph discussed developing a wireless phone in 1915, but were afraid deployment of the
technology could undermine its monopoly on wired service in the U.S.
The first commercial mobile phone service was launched in Japan by NTT in 1978. By November 2007, the total number of mobile phone subscriptions
in the world had reached 3.3 billion, or half of the human population (although some users have multiple subscriptions, or inactive subscriptions),
which also makes the mobile phone the most widely spread technology and the most common electronic device in the world.
The first mobile phone to enable internet connectivity and wireless email, the Nokia Communicator, was released in 1996, creating a new
category of expensive phones called smartphones. In 1999 the first mobile internet service was launched by NTT DoCoMo in Japan under the i-Mode
service. By 2007 over 798 million people around the world accessed the internet or equivalent mobile internet services such as WAP and i-Mode at
least occasionally using a mobile phone rather than a personal computer.
Cellular systems:
Mobile phones send and receive radio signals with any number of cell site base stations fitted with microwave antennas. These sites are usually
mounted on a tower, pole or building, located throughout populated areas, then connected to a cabled communication network and switching system.
The phones have a low-power transceiver that transmits voice and data to the nearest cell sites, normally not more than 8 to 13 km (approximately
5 to 8 miles) away.
When the mobile phone or data device is turned on, it registers with the mobile telephone exchange, or switch, with its unique identifiers,
and can then be alerted by the mobile switch when there is an incoming telephone call. The handset constantly listens for the strongest signal
being received from the surrounding base stations, and is able to switch seamlessly between sites. As the user moves around the network,
the "handoffs" are performed to allow the device to switch sites without interrupting the call.
Cell sites have relatively low-power (often only one or two watts) radio transmitters which broadcast their presence and relay communications
between the mobile handsets and the switch. The switch in turn connects the call to another subscriber of the same wireless service provider or
to the public telephone network, which includes the networks of other wireless carriers. Many of these sites are camouflaged to blend with
existing environments, particularly in scenic areas.
The dialogue between the handset and the cell site is a stream of digital data that includes digitized audio (except for the first generation
analog networks). The technology that achieves this depends on the system which the mobile phone operator has adopted. The technologies are
grouped by generation. The first-generation systems started in 1979 with Japan, are all analog and include AMPS and NMT. Second-generation
systems, started in 1991 in Finland, are all digital and include GSM, CDMA and TDMA.
The nature of cellular technology renders many phones vulnerable to 'cloning': anytime a cell phone moves out of coverage (for example, in a
road tunnel), when the signal is re-established, the phone sends out a 're-connect' signal to the nearest cell-tower, identifying itself and
signalling that it is again ready to transmit. With the proper equipment, it's possible to intercept the re-connect signal and encode the data
it contains into a 'blank' phone -- in all respects, the 'blank' is then an exact duplicate of the real phone and any calls made on the 'clone'
will be charged to the original account.
Third-generation (3G) networks, which are still being deployed, began in Japan in 2001. They are all digital, and offer high-speed data access
in addition to voice services and include W-CDMA (known also as UMTS), and CDMA2000 EV-DO. China will launch a third generation technology on
the TD-SCDMA standard. Operators use a mix of predesignated frequency bands determined by the network requirements and local regulations.
In an effort to limit the potential harm from having a transmitter close to the user's body, the first fixed/mobile cellular phones that had a
separate transmitter, vehicle-mounted antenna, and handset (known as car phones and bag phones) were limited to a maximum 3 watts Effective
Radiated Power. Modern handheld cellphones which must have the transmission antenna held inches from the user's skull are limited to a maximum
transmission power of 0.6 watts ERP. Regardless of the potential biological effects, the reduced transmission range of modern handheld phones
limits their usefulness in rural locations as compared to car/bag phones, and handhelds require that cell towers be spaced much closer together
to compensate for their lack of transmission power.
Some handhelds include an optional auxiliary antenna port on the back of the phone, which allows it to be connected to a large external antenna
and a 3 watt cellular booster. Alternately in fringe-reception areas, a cellular repeater may be used, which uses a long distance high-gain dish
antenna or yagi antenna to communicate with a cell tower far outside of normal range, and a repeater to rebroadcast on a small short-range local
antenna that allows any cellphone within a few meters to function properly.
Handsets:
Nokia is currently the world's largest manufacturer of mobile phones, with a global device market share of approximately 40% in 2008. Other major
mobile phone manufacturers (in order of market share) include Samsung (14%), Motorola (14%), Sony Ericsson (9%) and LG (7%). These manufacturers
account for over 80% of all mobile phones sold and produce phones for sale in most countries.
Other manufacturers include Apple Inc., Audiovox (now UTStarcom), Benefon, BenQ-Siemens, CECT, High Tech Computer Corporation (HTC), Fujitsu,
Kyocera, Mitsubishi Electric, NEC, Neonode, Panasonic (Matsushita Electric), Pantech Curitel, Philips, Research In Motion, Sagem, Sanyo, Sharp,
Siemens, Sendo, Sierra Wireless, SK Teletech, Sonim Technologies, T&A Alcatel, Huawei, Trium and Toshiba. There are also specialist communication
systems related to (but distinct from) mobile phones.
There are several categories of mobile phones, from basic phones to feature phones such as musicphones and cameraphones, to smartphones. The first
smartphone was the Nokia 9000 Communicator in 1996 which incorporated 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 N-Series of multimedia phones; and the Apple iPhone which provides full-featured web access and multimedia capabilities.
Mobile (Cell) Phones
Mobile phone features
Cell Phone Usage
Cell Phone Business Models
History of Cell Phones
History of the Telephone
History of the Telephone Controversy Debate and Patents
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