dual band mobile phone
In general, a distinction is made between dual-band and dual- mode cell phones, although the terms are often used synonymously.
If a cell phone supports a standard with two frequency ranges, it is a dual-band cell phone. This is the case, for example, with GSM networks with the different frequency ranges for the D network and the E network. The D network operates in the 900 MHz range, while the E network operates in the 1,800 MHz range.
If a cell phone is designed for three frequency ranges, it is a triple-band or tri-band cell phone, and if it has four frequency ranges, it is a quad-band cell phone. Such phones are available because, for example, the 450 MHz, 480 MHz, 850 MHz, 900 MHz, 1,800 MHz and 1,900 MHz frequency ranges are used for GSM in various countries.
Such triple- or quad-band cell phones are of interest to frequent travelers because the GSM standard in Europe uses the 900 MHz and 1,800 MHz frequency ranges, whereas the 850 MHz and 1,900 MHz frequency ranges are increasingly used in the United States.