A dual-band 900/1800 device is required to be compatible with most networks apart from deployments in
ITU Region 2.
GSM-900, EGSM/EGSM-900 and GSM-1800 GSM-900 and GSM-1800 are used in most parts of the world (ITU-Regions 1 and 3):
Africa,
Europe,
Middle East,
Asia (apart from
Japan and
South Korea where
GSM has never been introduced) and
Oceania. In common, GSM-900 is most widely used. Fewer operators use GSM-1800.
Mobile Communication Services on Aircraft (MCA) uses GSM-1800. In some countries, GSM-1800 is also referred to as "Digital Cellular System" (DCS).
GSM-850 and GSM-1900 GSM-1900 and GSM-850 are used in most of North, South and Central America (ITU-Region 2). In North America, GSM operates on the primary mobile communication bands 850 MHz and 1900 MHz. In
Canada, GSM-1900 is the primary band used in urban areas with 850 as a backup, and GSM-850 being the primary rural band. In the
United States, regulatory requirements determine which area can use which band. The term
Cellular is sometimes used to describe GSM services in the 850 MHz band, because the original
analog cellular mobile communication system was allocated in this spectrum. Further GSM-850 is also sometimes called
GSM-800 because this frequency range was known as the "800 MHz band" (for simplification) when it was first allocated for
AMPS in the United States in 1983. In
North America GSM-1900 is also referred to as
Personal Communications Service (PCS) like any other cellular system operating on the "1900 MHz band".
Frequency mixing between GSM 900/1800 and GSM 850/1900 Some countries in Central and South America have allocated spectrum in the 900 MHz and 1800 MHz bands for GSM in addition to the common GSM deployments at 850 MHz and 1900 MHz for ITU-Region 2 (Americas). The result therefore is a mixture of usage in the Americas that requires travelers to confirm that the devices they have are compatible with the bands of the network at their destination.
Frequency compatibility problems can be avoided through the use of multi-band (tri-band or, especially, quad-band) device. The following countries are mixing GSM 900/1800 and GSM 850/1900 bands:
GSM-450 Another less common GSM version is GSM-450. It uses the same band as, and can co-exist with, old analog
NMT systems. NMT is a first generation (
1G) mobile system which was primarily used in
Nordic countries,
Benelux,
Alpine Countries,
Eastern Europe and
Russia prior to the introduction of GSM. The
GSM Association claims one of its around 680 operator-members has a license to operate a GSM 450 network in
Tanzania. However, currently all active public operators in Tanzania use GSM 900/1800 MHz. There are no publicly advertised handsets for GSM-450 available. Very few NMT-450 networks remain in operation. Overall, where the 450 MHz NMT band has been licensed, the original analogue network has been closed, and sometimes replaced by
CDMA. Some of the CDMA networks have since upgraded from CDMA to
LTE (LTE band 31). == Multi-band and multi-mode phones ==