A digital mobile telephone system that is the most widely used wireless standard in the world. It is the dominant standard in Europe. It uses a type of TDMA (time-division multiple access). GSM digitizes and then compresses data before transmitting it down either a 900 MHz or 1800 MHz channel with two other streams of data, each with its own time slot. In the United States, AT&T Wireless Services Inc., Cingular Wireless, and Voice Stream Wireless Corp. use GSM technology.