Mobile radio is used primarily for dispatch applications by the emergency services, transport sector and utilities. Mobile radio services were introduced to alleviate the pressure on the mobile radio frequency bands through the introduction of trunking technology. Analogue mobile radio services are commonly known as Specialized Mobile Radio (SMR) services in the USA, and Public Access Mobile Radio (PAMR) in Europe and in Asia Pacific.

• SMR was introduced in the USA in 1979 and is designed for closed user group voice services with support for overlay packet data. It operates in the 800 MHz and 900 MHz spectrum and the radio equipment for the two bands is incompatible. SMR has around two million users in the USA but only 150,000 use data (Source:GRS Company, end-1996). There are many local and regional operators but licenses are not awarded for national networks.

• PAMR services in Europe and Asia Pacific tend to use the MPT 1327 specification for trunked networks which originated in the UK in 1985. By mid-1997 there were several hundred national and local networks operating in Europe and Asia Pacific, many offering data services. The standard has been extended to incorporate data transmitted over specially designated data channels. There are several thousand data users in Europe and in Asia Pacific.

Digital services with data services as a common feature are being introduced using either proprietary technology from the leading suppliers or the European TETRA or USA APCO25 standard.

PHS (Personal Handyphone System)

PHS was developed in Japan and enables a cordless phone to be used at home or in the office and outside like a cellular phone. It is designed for service in heavily populated metropolitan areas and in commuter spots such as subway stations, office complexes and shopping malls - areas where cellular technology typically has problems due to the shielding of signals by the buildings. It is possible for two terminals to be used in direct mode even when outside the range of a base station, unlike cellular. Other cordless services using earlier technology were unsuccessful, but the growth of PHS has been astounding with 4.9 million subscribers at the end of 1996 and 6.42 million by April 1997 (Source: GRS Company). Services are being introduced in Australia, China and Indonesia and other nations evaluating the technology.