A 2G digital cellular radio standard from the Electronics Industry Alliance (EIA) and Telecommunications Industry Association (TIA) and later approved by the American National Standards Institute (ANSI) to officially become ANSI/TIA/EIA-567. IS-54 is an extension of the analog Advanced Mobile Phone System (AMPS) and is commonly known as Digital AMPS (DAMPS) and United States Digital Cellular (USDC). IS-54 evolved into IS-136.The two standards jointly specified the time division multiple access (TDMA) method and are often referred to as TDMA. See also 2G, ANSI, cellular radio, D-AMPS, EIA, IS-136, TIA, and TDMA.