A mobile phone is a portable telephone that can make and receive calls over a radio frequency carrier while the user is moving with in a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network.
All mobile phones have a variety of features in common, but manufactures seek product differentiation by adding functions to attract consumers. This competition had led to great innovation in mobile phone development over the past 20 years. A battery, providing the power source for the phone functions, an input mechanism to allow the user to interact with the phone. The most input mechanism is a keypad, but touchscreens are also found in most smartphones.
Some cell phones use one antenna as the transmitter and receiver while others, such as the iPhone 5, have multiple transmitting or receiving antennas. An antenna is a metallic element (such as copper) engineered to be a specific size and shape for transmitting and receiving specific frequencies of radio waves.
The world's largest individual mobile operator by number of subscribers is China Mobile, which has over 500 million mobile phone subscribers.Over 50 mobile operators have over ten million subscribers each, and over 150 mobile operators had at least one million subscribers by the end of 2009.In 2014, there were more than seven billion mobile phone subscribers worldwide, a number that is expected to keep growing.
Mobile phones are used for a variety of purposes, such as keeping in touch with family members, for conducting business, and in order to have access to a telephone in the event of an emergency. Some people carry more than one mobile phone for different purposes, such as for business and personal use. Multiple SIM cards may be used to take advantage of the benefits of different calling plans. For example, a particular plan might provide for cheaper local calls, long-distance calls, international calls, or roaming.
By Paea Pomana