GSM Frequency Bands - Multi-band and Multi-mode Phones

Multi-band and Multi-mode Phones

Today, most telephones support multiple bands as used in different countries to facilitate roaming. These are typically referred to as multi-band phones. Dual-band phones can cover GSM networks in pairs such as 900 and 1,800 MHz frequencies (Europe, Asia, Australia and Brazil) or 850 and 1900 (North America and Brazil). European tri-band phones typically cover the 900, 1800 and 1900 bands giving good coverage in Europe and allowing limited use in North America, while North American tri-band phones utilize 850, 1,800 and 1,900 for widespread North American service but limited worldwide use. A new addition has been the quad-band phone, also known as a world phone, supporting all four major GSM bands, allowing for global use (excluding non-GSM countries such as Japan or South Korea).

There are also multi-mode phones which can operate on GSM as well as on other mobile phone systems using other technical standards or proprietary technologies. Often these phones use multiple frequency bands as well. For example, one version of the Nokia 6340i GAIT phone sold in North America can operate on GSM-1900, GSM-850 and legacy TDMA-1900, TDMA-800, and AMPS-800, making it both multi-mode and multi-band. As a more recent example the Apple iPhone 5 and iPhone 4S support quad-band GSM at 850/900/1,800/1,900 MHz, quad-band UMTS/HSDPA/HSUPA at 850/900/1,900/2,100 MHz, and dual-band CDMA EV-DO Rev. A at 800/1,900 MHz, for a total of 'six' different frequencies (though at most four in a single mode). This allows the same handset to be sold for AT&T Mobility, Verizon, and Sprint in the U.S. as well as a broad range of GSM carriers worldwide such as Vodafone, Orange and T-Mobile (Excluding-US), many of whom offer official unlocking.

Note that while the Nexus One, like many other devices on the market, may also become available in a UMTS I/II/IV or 2,100/1,900/850 MHz combo, it would still be considered tri-band UMTS, not quad-band, as the hardware is limited to supporting any three bands at one time. Further, as HSPA runs atop UMTS, it would not be considered a "mode" by strict definition.