The mobile phone, unlike the traditional, analogue telephone, uses electromagnetic radio waves to transmit and receive voice, and other data, without the need for wires. The digital technology employed by a mobile phone converts the analogue sound wave of the human voice into series of discrete numbers, or digits, and is also suitable for the transmission of other data, such as text messages, digital photographs, or MP3 music files. A mobile phone requires access to a mobile phone network – in other words, a collection of radio masts situated up and down the country – operated by a service provider, such as Orange, Vodafone, or T-Mobile. Each service provider offers a number of different services, either "pay as you go", which, as the name suggests, allows you to buy credit as, and when, required, or monthly line rental, where you pay flat-rate fee, regardless of the volume of calls you make.
Text messaging is a standard feature of most, if not all, modern mobile phones, and allows you to send messages, created via the buttons on the handset, to the screen of another mobile phone.
Many mobile phones, nowadays, also include the facility to record digital images, still, or video. Advances in camera, and phone, technology mean these images are sufficiently high resolution to be used outside mobile devices, for example, for distribution by email, or via the Internet. Any mobile phone camera with a resolution of ½Mp, or above, is likely to be suitable for this purpose, and cameras with resolutions of 3Mp, or 5Mp, are becoming increasingly common.
Support for WAP, or "Wireless Application Protocol", allows a mobile phone to connect to the wireless Web using a GPRS ("General Packet Radio Service"), or 3G, connection. 3G is the latest multimedia technology, allowing online gaming, video messaging, etc.. Some mobile websites offer access to streaming video and audio – by subscription, or, more recently, free – which can be watched, or listened to, on a mobile phone.
Another useful feature to look out for, when buying cordless digital phones, is infrared, or Bluetooth connectivity. Bluetooth, for example, allows you to connect, wirelessly, to accessories, such as headsets, at a range of up to 30 feet, or so, while infrared can be used, at shorter distances, to exchange information with personal computers, or other external devices, if they are also equipped with infrared.