Total Access Communications System (TACS) is a cellular analog mobile communications system based on Advanced Mobile Phone System (AMPS). It was deployed in Europe in the 900 MHzfrequency range and formed the transition from 1st generation (1G) analogmobile networks to 2nd generation (2G) cellular and digital
mobile networks. The frequency ranges of TACS are between 90 MHz and 915 MHz and between 935 MHz and 960 MHz. These are the frequency ranges that were later used for GSM. The channel width of TACS was 25 kHz, the modulation method was frequency modulation and the access method was Frequency Division Multiple Access (FDMA). The Japanese variant of TACS was called JTACS and had an additional frequency band. In addition, there is a version developed in England, the Extended Total Access Communications System (ETACS), in which more radio channels can be assigned.