(Total Access Communication System) An analog cellular phone system deployed mostly in Europe. It was modeled after the AMPS system in the U.S. In the U.K., ETACS (Extended TACS) transmits in the 871-904/916-949 MHz band. International TACS (ITACS) and International ETACS (IETACS) are versions that operate outside the U.K. Narrowband TACS (NTACS) operates in the 860-870/915-925 MHz band, and by using a narrower channel spacing, delivers more channels in the same amount of spectrum. See AMPS.