0G refers to pre-cellular mobile telephony technology. These mobile telephones were usually mounted in cars or trucks, though briefcase models were also made. Typically, the transceiver (transmitter-receiver) was mounted in the vehicle trunk and attached to the "head" (dial, display, and handset) mounted near the driver seat. Push to talk, commonly abbreviated as PTT, is a method of conversing on half-duplex communication lines, including two-way radio, using a button to switch from voice transmission mode to voice reception mode. ... Mobile Telephone System (MTS) was one of the earliest mobile telephone standards. ... The Improved Mobile Telephone Service (IMTS) is a pre-cellular VHF/UHF radio system that links to the PSTN. IMTS was the radiotelephone equivalent of land dial phone service. ... The Advanced Mobile Telephone System was a 0G method of radio communication, mainly used in Japanese portable radio systems. ... Autotel (also called PALM, or Public Automated Land Mobile) is a radiotelephone service which was the missing link between earlier MTS/IMTS and later cellular telephone services. ... ARP (Autoradiopuhelin, Car Radio Phone in English) was the first commercially operated public mobile phone network in Finland. ... 1G (or 1-G) is short for first-generation wireless telephone technology, cellphones. ... For other meanings of the abbreviation, see: NMT. NMT (Nordisk MobilTelefoni or Nordiska MobilTelefoni-gruppen, Nordic Mobile Telephone in English) is a mobile phone system that was specified by the Nordic telecommunications administrations (PTTs) starting in 1970, and opened for service in 1981 as a response to the increasing congestion... Advanced Mobile Phone System or AMPS is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1984. ... hicap is a mobile techonology which has a consumer interface with a wide variety of industry references. ... Cellular Digital Packet Data (CDPD) uses unused bandwidth normally used by AMPS mobile phones between 800 and 900 MHz to transfer data. ... Mobitex is a paging network developed by Ericsson. ... DataTac is a wireless data network technology originally developed by Motorola and deployed in the United States as the ARDIS network. ... 2G (or 2-G) is short for second-generation wireless telephone technology. ... The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ... Iden is also a village in East Sussex, England Integrated Digital Enhanced Network, commonly referred to as iDEN, is a mobile communications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. ... IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS). ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Personal Digital Cellular (PDC) is a 2G mobile phone standard developed and used exclusively in Japan. ... Circuit Switched Data, often known as CSD, is the original form of data transmission developed for the GSM mobile phone system. ... 2. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM mobile phones. ... High-Speed Circuit-Switched Data (HSCSD), is a development of Circuit Switched Data, the original data transmission mechanism of the GSM mobile phone system. ... Wideband Integrated Dispatch Enhanced Network, or WiDEN, is a software upgrade developed by Motorola for its iDEN enhanced specialised mobile radio (or ESMR) wireless telephony protocol. ... A 2G mobile phone is a circuit switched digital mobile phone. ... CDMA2000 is a family of 3G mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signaling data (such as a dialed telephone number) between mobile telephones and cell sites. ... Enhanced Data rates for GSM Evolution (EDGE) is a digital mobile phone technology which acts as a bolt-on enhancement to 2G and 2. ... 3G (or 3-G) is short for third-generation mobile telephone technology. ... W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ... FOMA, officially short for Freedom of Mobile Multimedia Access, is the brand name for the 3G services being offered by Japanese mobile phone operator NTT DoCoMo. ... CDMA2000 is a family of 3G mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signaling data (such as a dialed telephone number) between mobile telephones and cell sites. ... TD-SCDMA (Time Division Synchronous Code Division Multiple Access) is a 3G mobile telecommunications standard, being pursued in the Peoples Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang and Siemens AG, in an attempt to develop home-grown technology and not be dependent on Western... High-Speed Downlink Packet Access or HSDPA is a new mobile telephony protocol. ... HSUPA, High-Speed Uplink Packet Access, is a data access protocol for mobile phone networks with extremely high upload speeds up to 5. ... 4G (or 4-G) is short for fourth-generation the successor of 3G and is a wireless access technology. ...

They were sold through WCCs (Wireline Common Carriers, AKA telephone companies), RCCs (Radio Common Carriers), and two-way radio dealers. The primary users were loggers, construction foremen, realtors, and celebrities.

Early examples for this technology are:

• the Autoradiopuhelin (ARP) launched in 1971 in Finland as the country's first public commercial mobile phone network
• the B-Netz launched 1972 in Germany as the countries second public commercial mobile phone network (but the first one that did not require human operators anymore to connect calls)