Mobile phones

A mobile phone allows calls into the public switched telephone system over a radio link. Early mobile phones were usually bulky and permanently installed in vehicles; they provided limited service because only a few frequencies were available for a geographic area. Modern cellular "cell" phones or hand phones make use of the cellular network concept, where frequencies are re-used repeatedly within a city area, allowing many more users to share access to the radio bandwidth. A mobile phone allows calls to be placed over a wide geographic area; generally the user is a subscriber to the phone service and does not own the base station. By contrast, a cordless telephone is used only within the range of a single, private base station.