A mobile phone, also known as a cellular, cell, mobile, or hand phone, is an electronic telecommunications device with the same basic capability as a conventional fixed line telephone, but which is also entirely portable and is not required to be connected with a wire to the telephone network. Most current mobile phones connect instead to the network using a wireless radio wave transmission technology. The mobile phone communicates via a network of base stations which are in turn linked to the conventional telephone network.
In addition to the standard voice function of a telephone, a mobile phone can support many additional services such as SMS for text messaging, packet switching for access to the Internet and MMS for sending and receiving photos and video.
Some of the world's largest mobile phone manufacturers include Alcatel, Audiovox, Fujitsu, Kyocera (formerly the handset division of Qualcomm), LG, Motorola, NEC, Nokia, Panasonic (Matsushita Electric), Philips, Sagem, Samsung, Sanyo, Sharp, Siemens, SK Teletech, Sony Ericsson, and Toshiba.
Mobile phones are often packed with features that offer users far more than just the capability to send text messages and make voice calls. These may include internet browsing, music (MP3) playback, personal organisers, email, watch/alarm, built-in cameras, ringtones, security measures (e.g. pin codes), SIM blocks, games, radio, Push to talk, infrared and bluetooth connectivity, and call registers.
Mobiles are designed to work on cellular networks and contain a standard set of services that allow phones of different types and in different countries to communicate with each other.
Before the phone can be used, a subscription to a mobile phone operator (a.k.a. carrier) is required. For phones on GSM networks, the operator will issue a SIM card which contains the unique subscription and authentication parameters for that customer; alternatively, the carrier will put the customer's handset identifier into its subscriber database so that the handset can make calls on the network. Once the SIM card is inserted into the phone, services can be accessed. Many mobile phones support 'auto-roaming', which permits the same phone to be used in multiple countries. For this to work, the operators of both countries must have a roaming agreement.
Mobile phones do not only support voice calls; they can also send and receive data and faxes (if a computer is attached), send short messages (or "text messages"; see SMS), access WAP services, and provide full Internet access using technologies such as GPRS. Mobile phones usually have a clock and a calculator and often one can play some games on them.
Most current models also allow for sending and receiving pictures and have a built-in digital camera. Sound and video recording is often also possible. This feature is generally referred to as MMS. This gives rise to some concern about privacy, in view of possible voyeurism, for example in swimming pools. For this reason, Saudi Arabia has entirely banned the sale of camera phones (although the country allows pilgrims on the Hajj to bring in camera phones); South Korea has ordered manufacturers to ensure that all new handsets emit a beep whenever a picture is taken.
GPS receivers are starting to appear integrated or connected (i.e. using bluetooth) to cell phones, primarily to aid in dispatching emergency responders and road tow truck services. This feature is generally referred to as E911.
Push to talk, available on some mobile phones, is a feature that allows the user to talk to another by pressing the button. It functions similar to walkie-talkie.
MP3 is a popular digital audio encoding and lossy compression format invented and standardized in 1991 by a team of engineers working in the framework of the ISO/IEC MPEG audio committee under the chairmanship of Professor Hans Musmann (University of Hannover - Germany). It was designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. In popular usage, MP3 also refers to files of sound or music recordings stored in the MP3 format on computers. Many 3G mobile phones include MP3 players with high audio quality and media cards to store MP3 files so the cell phone can be used to listen to music anywhere. Playing MP3 files in mobiles usually speeds up the battery charge loss.