NMT 【Nordisk MobilTelefoni】
full spelling ： Nordic Mobile Telephony
NMT (Nordisk MobilTelefoni or Nordic Mobile Telephony in English) is a mobile phone system first came in to service in 1981. NMT is a first generation or 1G mobile phone system. There are two variants of NMT networks, NMT-450 and NMT-900. NMT-450 network was first introduced and NMT-900 was introduced in 1986. NMT-900 carries more channels than the previous NMT-450 network.
NMT used full duplex transmission, allowing for simultaneous receiving and transmission of voice. NMT standard specified billing as well as national and international roaming. The NMT specifications were free and open. This allowed many companies to produce NMT hardware.
The NMT network has mainly been used in the Nordic countries, Baltic countries, Russia and also in some Middle East and in Asian countries. The introduction of digital mobile networks such as GSM has reduced the popularity of NMT networks.