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A mobile phone (also known as a wireless phone or cell phone ) is a short-range, electronic device used for mobile voice or data communication over a network of specialised base stations known as cell sites. In addition to the standard voice function of a mobile phone, 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).

Overview

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 multi-use devices 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 digitised 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 miniaturisation 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.

Features

Mobile phones often have features beyond sending text messages and making voice calls, including Internet browsing, music (MP3) playback, memo recording, personal organiser functions, e-mail, instant messaging, built-in cameras and camcorders, ringtones, games, radio, Push-to-Talk (PTT), infrared and Bluetooth connectivity, call registers, ability to watch streaming video or download video for later viewing, video calling and serve as a wireless modem for a PC, and soon will also serve as a console of sorts to online games and other high quality games. The total value of mobile data services exceeds the value of paid services on the Internet, and was worth 31 billion dollars in 2006 (source Informa). The largest categories of mobile services are music, picture downloads, videogaming, adult entertainment, gambling, video/TV.

Nokia and the University of Cambridge are showing off a bendable cell phone called Morph .

Applications

The most commonly used data application on mobile phones is SMS text messaging, with 74% of all mobile phone users as active users (over 2.4 billion out of 3.3 billion total subscriber

Here are the new top-five cell phone manufacturers based on their market share:Fresh news, news, cell phone, handset

Netbooks like the Asus Eee PC will soon cost $99. The catch? You'll need to commit to a two-year mobile broadband contract, just like your cell phone. Why so low? 1) the economy; 2) the cell phone sales crash; 3) the netebook explosion; 4) the netbook glut; 5) the netbook's Internet dependency; 6) the backlash against 3G; and 7) Moore's Law!

Recently the Samsung Omnia have been released in Japan, with an official name of SoftBank 930SC Omnia. Apparently there are some differences between the regular one and the Japanese style one.Samsung, Omnia, cell phone, handset

Register today for a free trial, credit card req'd. Find Washington Informer articles plus many other academic journal articles, magazine articles & newspaper archives.

Cell Phone Dermatitis. Have you heard about this? Check this article out.

chantrella asks: "I am on cingular service and wondering if my cell phone will work when i go on my carnival cruise to the bahammas? will it work on ship? in freeport? in nassau?"

jess00808 replies: 'Call 611 and ask them.. I vacationed in a US territory of the caribbean and still had service although someone else had my number so I couldn't recieve calls. There wasn't an extra charge.'

valleylow00 replies: 'Well I just recently went on a Cruise and found that while out at sea I had no service but once we got close to shore I had service and could make calls from my phone. I however went on Carnivals Mexican Riviera cruise so I can say for sure if you service will be the same, but I imagine it would work when you are close to land.'

crazy_cat_lady replies: 'Go to and look at your coverage area to see if you have service in those areas.'

ArubaLisa replies: 'For details on Cingular and CarnivalFor details on Cingular and the Bahamas'

silverdust800 replies: 'it will work but it cost extra and the fee is a real ripoff like 2 dollers per min.'

eviekw replies: 'If there is any service in those places, you will probably be roaming. I traveled with my Sprint cell to Cozumel, Grand Caiman and Jamaica, and was able to roam in all of them. You will not have service while at open sea. Check your carrier roaming fees.'

gojenni714 replies: 'It may work, but there is a killer service charge. We were warned about it when we sailed to the Mexican Riveria with Royal Caribbean. In international waters, most cell phone companies charge like, $5 a minute. It was steep and certainly not worth it.'

Shawn Gates asks: "I got my cell phone taken away because I got a C+. My step-dad thinks that I have to have all A's and B's. I don't think it is fair getting it taken away over one C+. I want to get my grades up but the end of school is tomorrow. What is a good way to fix my grades or get my cell phone back?"

pubes replies: 'get better grades? in the meantime, demonstrate your hard work by doing your homework early and stuff. my parents got mad at me today for getting 5 A's and 1 C and theyre happy when i get straight B's. seriously -_-'

vivek1677 replies: 'ah man..work for it..or wait till you buy your own'

Krafty13 replies: 'Ask you teacher if there's any extra credit you can do to get your grades up. It's a quick and sometimes easy way to not only get them up, but show your parents and teachers you actually care about your grades. Assuming you do care about your grades....'

melody replies: 'if u noe where the fone is just take it wen no ones around. too late to get ur grades up but u could go to summer school and get good grades there'

Super Nova asks: "I want a cell phone that I can text and take pictures on. What company in the United States is the cheapest like on the cell phone bill that you pay monthly? Also, I want to know if they have good cell phone plans too. Thank you to all who answer my question.Anybody who is familar with Denver, Colorado. What cell phone company is best here?"

ashash replies: 'you should go with verizon.its great.thats what my whole family has.'

legendarysim@sbcglobal.net replies: 'T-Mobile is the most bang for your buck while having a pretty reliable network. You can get about 1,000 minutes for about 39.99 and an unlimited texting plan is usually 15-20 additional dollars a month.If you have plans to talk a lot on your phone I would go with Sprint. Sprint has plans such as purely unlimited or all incoming calls or free.'

8 Track Mind replies: 'i have been with every single major carrier, and some smaller ones as well. cingular has the best overall service nationwide. i dropped fewer calls, had less problems with customer service and billing with them than anyone else. cheapest? cricket in phoenix.'

Linz [NBT] replies: 'Cingular/now called AT&T is the best.'

mcrfreak983 replies: 'Tracfone is the cheapest- It is pay as you go and has no contracts or bills. You add airtime thro cards from walmart or target. Hope i helped!! <3<3<3'

Mehak replies: 'i would like to kno too.'

Farmer Brown replies: 'get verizon and pick the Samsung Alias is a awsome phone..i have it and its cool'

Stu B replies: 'Tmobile is probably your best choice because you can get 300 minutes and unlimited texting for one person for about 40 dollars. And if you have a family its even better because you can get any plan you want including myfaves plan which lets you talk to any 5 people for free and you can get unlimited texting for your entire family which includes basic text messages, picture messages, video messages, and voice messages. The picture video and voice messaging usually needs an additional charge on other phone companys when it is only 10 dollars a month for all of it.'

A.Ganapathy India replies: 'That depends upon the country you live. For India Nokio is the best and cheap one .It has different range to suit the need of different section of people.'

granny replies: 'I am with AT&T (formerly Cingular). I like them. When they sold to Cingular I was very unhappy, but now they bought it back and I am happy with them. Basically, you get what you pay for. Cheap is not good. Also, check out the deals they may have instore. Talk and go is one with AT&T. No contract and you pay as you go. Don't know about phone quality on that one.'

wshao55 replies: 'Verizon.'

seb replies: 'I can tell you one thing: Do not get Sprint. There are not many great phones, and the bills can be extrememly surprising. Sprint also has been shown to have terrible reception in many places. You could loose your calls in a snap... also, their phones were sort of cheap and 'cruddy' when I got them. My family got fed up and switched to Verizon, and it is great. First off, I saw a major improvement in their phones. There aren't any cheapo phones that don't work. The reception is also great - but the bills can be high (sometimes), dependin on your plan.If you want more for your money, though T-Mobile is the way to go. The plans are unbeatable. There is one issue: not many people use T-Moblie, making your minutes go up higher when you talk to people out of your network.There are also some wireless carriers I would not reccomend:- Altel Wireless- NextelAT&T is also supposed to be great. They have some great phones, but most of them do not have that many features such as music, internet, and so on. :]Hope i helped! -seb'

Kit Kat replies: 'AT&T all of my family members have it and it's really cheep.or verison'

christinaaa! <333 replies: 'Diffidently Verizon! its so rely able and has really nice phones!'

Mr. Smooth replies: 'Metro PCS'

ABBY S replies: 'My parents and family insist on AT&T (Cingular) which is OK except I want T-mobile because I'm a big texter and i want a full qwerty keyboard without getting a blackberry or a blackjack. AT&T is good for families because of the whole deals they give like buy one phone and get three more. Plus texting unlimited is pretty dang cheap. Oh but, waiting for an upgrade takes forever! 2 years after purchase of current phone. Rippp-offf! Thye have alot of phones that have cameras and some of them other stuff too, for instance my ad has the sync which has the built in stuff but he has 3 ipod nanos already! AND YOU CAN TEXT ON EVERY PHONE. EVERY PLAN and COMPANY has that. Just make sure it's enabled :) Btw, I live in Denver. Isnt that weird (IDK, im suger high rite now)'

Wendy G replies: 'AT&T ALL THE WAY!!!1. They have the very best service.2. For price, you can get the GO Phone for $20 and pay as you go. For the record, my husband is employed by AT&T yellowpages. SBC, formerly Southwestern Bell Corp. owned Cingular. The reason Cingular became AT&T is because SBC bought out AT&T and took on that name for global name recognition.'

Anthony L replies: 'You might want T-mobile. They have plans that will give you 400 minutes for $30, but if you want myFaves, it is only $10 more. otherwise they have a lot of phones that I have tested and so far, all of my favorites have been T-mobile of Virgin Mobile.'

L!LCUT!3 replies: 'Verizon because ity has ring backs if you like to listen to music and gots more and cheapbut i will also go us cellular because if u like to text then its unlimited and way cheaper'

brianna watson replies: 'i would say at&t because i like them and the do have a good deal on stuff because i just got my new cell phone from them a couple of hours ago and the had taken 130.00 dollars off my phone from a plan they sent in the mail.ao i would defintily say at&t or cingular.'

K K replies: 'AT&T!!! It has the best phones EVER! I just got the new LG shine and I love it! They have so many other cool phones tho and i couldnt decide! Go with AT&T its the best! ANd very helpful too!'

photoshop.artbosco p replies: 'Try to choose verizon or nokiait is really good phones'

Ta da! replies: 'Cricket and yes they have good phones. If you decide to go with a Cricket plan I have an #800 to call for customer service where the people on the other end of the line are located in the United States. The number they give you to call when you sign up is for a service center out of the country; the people at the Cricket store will tell you they don't have a toll free number for the US but I found it!'

wzp replies: 'sprint'

Jennifer replies: 'Im not to sure if they are in your area, but check out MetroPCS. I pay $61.58 a month for unlimited EVERYTHING. Phone, text, email and web. They have some really cool phones, but nothing like the iPhone or the SPrint Moguel.'

jonathannunes2002 replies: 'I love Virgin Moblie. You can pay as you go and you can also get a monthy no-contract plan. If you want to go cheap go with with Virgin Mobile. If you don't need to spend a certain amount of money go with At&t'

monita replies: 'check if you have cricket around they have some good plans for texting also what u can do is check what service your friends have the most, that way you can get free mobile to mobile and you wont have to paythat much for the service.'

fillipinaprincess replies: 'I hate Verizon, their phones suckkk!! And their service sometimes too!We have t-mobile, I like the plans they offer, especially the phones for texting. But AT&T is good, although I have friends that have broken 6 at&t phones in the past year.'

rlkeebler asks: "I have flown several times since 9/11. Twice going to and from New York and Oregon and several flights to Arizona to Oregon and back. In each flight I would turn on my cell phone to see if I could get a connection. I always got no service available to apear on my sceen.About a year ago I read on the internet that in order for people to use cell phones on flying aircraft the airplanes would need to have a special antenna installed. This has not begun to happen yet.So my question would be. If you can not get service on your cell phone while flying in an airplane. On 9/11 how did the people on board those doomed aicraft manage to use their cell phone to call out to their loved ones? I'm not counting the people who used the available at great cost aircraft phones just the ones who are said to have used their cell phones.Just one of the holes in the vast 9/11 story."

ca_surveyor replies: 'In general you can not use your cell phone because the signal on your cell phone is designed to reach a cell tower within about 6 miles of your position. At 200 mph those towers go by awful fast. At two miles up the plane must be within 5 miles of the tower. That means you have about a minute and a half to catch the signal and get a lock. Since a lot of flights pass over undeveloped terrain (mountains, deserts, etc..) that connection is almost sure to be broken within about 3 minutes even if you get it. A general exception to this is when a plane circles to await a landing. You can almost always get a signal and place a call then.. (until the flight attendant catches you).Some planes are equipped with a repeater antenna which will pick up your cell signals and relay them to a base station which link back with the cell system. Obviously this service is not free.In 9/11 it was my understanding that the hijackers allowed the passengers to use the standard seat phones (available on almost all planes) to call home. These phones are wireless but not cell phones, so they can operate anywhere within the cabin of the plane much the same as wireless phones can work within your house.'

Flyboy replies: 'No, it's not a hole in the 9/11 story. In many cases, you can get a signal in an airplane, especially with a good digital phone, and depending on the tower configuration on the ground. Also, as the previous answer pointed out, and the info linked below shows, most of the calls were placed from Airphones, which are not cell phones, and work at any altitude and speed.If you're going to try and trot out "facts" to support your conspiracy theory, make sure you know what you're talking about.'

my2cents replies: 'I've accidentally left my cell on during flights to Ohare and to DFW. When I discovered my mistake, I was surprised to see that the signal was still good although I did not try to make a call. I know that my cell phone signal could cause interference with sensitive electronics as I found out when my cell rang during a visit to a friend in the hospital. I agree with the technical concerns.Interestingly, I was told by a friend that works for Verizon that besides the interference issues, there is also an expense/accounting issue. In remote areas, you may pass through an area that is covered by towers not owned by your primary Provider (i.e. You're "roaming"). This coverage triggers billing to your Provider even if you don't use the phone. As you can imagine, when in a plane, this would happen quite often and notably increase their costs. I think this is less of a problem now with improved technology and primary coverage.PS. I'm no conspiracy theorist.'

Sul replies: 'The people on the 9/11 flights used seatback Airphones as others in this forum have stated. As a general rule cell phones don't work very well above about 7000 feet. Some airlines have explored the possibility of installing a device, similar in concept to a computer router, that would enable passengers to use personal cellphones while at cruise altitude. It will be expensive to install and and maintain so you can bet the airlines will charge for it. My2cents is correct, one of the main reasons for the ban by the FCC on cellphones is the accounting issue.'

ALOPILOT replies: 'There are many more cell phone towers in the east than over states like Utah, Nevada, ect.... also, maybe your cell phone isnt as good as theirs... Don't doubt the heroics of the passengers on United 93... or their stories... Also, I hope you get caught next time and fined the maximum $10,000 and jailed for failing to comply with crewmember instructions... :-) have a nice day'

Kamikaze asks: "I need the cheapest cell phone possible. Both my home phone and cell phone aren't working and I need something that doesn't include a plan or long sign up process. I've heard that there's cheap cell phones you can buy, or even use your own, then just buy minutes as you use them each month. Where can I find something like this and what is it exactly?"

Lauren Bee!! replies: 'The tracfone or what i have is Virgin mobile and i just bought the phone and card and activated it and that was it. Now i got a fone.'

slmolevhqlbxv replies: 'the cheapest is virgin mobile.'

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