Range of radio frequencies between two defined limits which are used in wireless communications. 800 to 1900 MHz is the band used for CDMA. Whereas 900-1800 and 1900 are used for GSM. Not all phones use the same frequencybands. For instance, GSMcell phones used in Europe work either on the 900 or 1800 megahertz (Mhz) frequencyband while American GSMphones use the 1900 Mhzband. Thus, they can't be used in Europe. But most phones today are triband, which means they have all three frequencies and can be used worldwide.