In telecommunications, a multi-band device (including (2) dual-band, (3) tri-band, (4) quad-band and (5) penta-band devices) is a communication device (especially a mobile phone) that supports multiple radio frequency bands. All devices which have more than one channel use multiple frequencies; a band however is a group of frequencies containing many channels. Multiple bands in mobile devices support roaming between different regions where different standards are used for mobile telephone services. Where the bands are widely separated in frequency, parallel transmit and receive signal path circuits must be provided, which increases the cost, complexity and power demand of multi-band devices.[citation needed]
The term quad-band describes a device that supports four frequency bands: the 850 and 1900 MHz bands, which are used in the Americas, and 900 / 1800, which are used in most other parts of the world.[1] Most GSM/UMTS phones support all four bands, while most CDMA2000/1xRTT phones (mostly North America and voice transmission only) do not, and so are considered only dual-band devices. A few phones support both of the domestic frequencies but only one foreign one for limited roaming, making them tri-band phones.[citation needed]
The term penta-band describes a device that supports a fifth frequency band, commonly the 1700/2100 MHz band in much of the world. The Advanced Wireless Services (AWS) 1700 MHz band is also seeing increased usage.[citation needed]
4G LTE bands
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AT&T Mobility devices use former TV channel 53 and 54 nationwide and has purchased spectrum from former TV channel 55 nationwide (purchased from Qualcomm's defunct MediaFLOpay TV service), and also channel 56 in densely populated areas such as California and the Northeast Corridor. Verizon Wireless formerly held frequencies just above TV channel 51, which is still in use, causing adjacent-channel interference that is preventing the carrier from using them until the planned top-down spectrum repacking occurs. The channel 52 spectrum was later purchased by T-Mobile US who now uses this spectrum for their network. Verizon now uses higher blocks within the former TV band (channels 60 and 61).[citation needed]
See also
List of UMTS networks around the world, and the frequencies and data rates they support