mobile phone

Cordless telephone linked to a cellular radio network. Early cellular networks used analogue technology, but since the late 1990s most services use a digital system. Calls are linked to the public telephone system via a network of connected base stations and exchanges; the area covered by each base station is called a cell. Each cell is about 5 km/3 mi across, and has a separate low-power transmitter. Mobility is possible as calls can be made while moving from one radio cell to another. In Europe, GSM (Global System for Mobile communications) has been adopted by many countries as a digital standard, enabling travellers to use a single phone across different national networks. Tri-band mobile phones are capable of changing frequencies to allow local networks in the USA to be accessed.

A trend for greater integration of phone and computer led to the development of WAP (wireless application protocol) phones in 1999. These allowed users to read e-mails and browse the Web, and by 2002 users could send digital images using a built-in digital camera. High-speed, ‘third generation’ (3G) phones were launched, capable of sending and receiving video messages, video calling, e-mail, photo-messaging, and news and information services (see 3G). Other potential applications include interactive television and all the features of a personal digital assistant (PDA).

In June 2001, New York became the first US state to ban motorists using mobile phones; violation of the law would incur a US$100 fine for the first violation, US$200 for the second, and US$500 for subsequent infringements. More than 40 other states proposed similar bans.

Mobile phone services rely on an internal Subscriber Identity Module (SIM) card. The SIM card identifies the phone to its network, can store telephone numbers, and protects users against misuse of their network account. Most mobile phone services offer a service called SMS messaging, which allows users to send each other text messages. GPRS (General Packet Radio Services) allows users to have their mobile phones permanently connected to the Internet.

Health risks Some scientific research has found a link between mobile phone use and brain tumour incidence but the proof is far from conclusive. To determine whether there is a risk, the World Health Organization (WHO) launched the International EMF (electromagnetic field) Project in 1996. Intended to run until 2005, the project aims to determine the effects on human health of all devices that produce EMFs, including mobile phones. As of early 2004, there was no scientific proof that mobiles cause any more harm than increasing the temperature of the head by a harmless amount. Nevertheless, UK government health recommendations were that mobile phone users, especially children, should only use the phones for short periods and avoid prolonged activity if possible.

Mobile phone transmitting masts have sprung up all over the industrialized world. Many people living within close range of masts maintain that they are responsible for an increase in cancers and other illnesses.