Mobile rigs were the beginning of mobile phones for use in vehicles such as taxicab radios, two way radios in police cruisers, and the like. A large community of mobile radio users, known as the mobileers, popularized the technology that would eventually give way to the mobile phone. Originally, mobile phones were permanently installed in vehicles, but later versions such as the so-called transportables or "bag phones" were equipped with a cigarette lighter plug so that they could also be carried, and thus could be used as either mobile or as portable phones
In December 1947, Douglas H. Ring and W. Rae Young, Bell Labs engineers, proposed hexagonal cells for mobile phones. Philip T. Porter, also of Bell Labs, proposed that the cell towers be at the corners of the hexagons rather than the centers and have directional antennas that would transmit/receive in 3 directions (see picture at left) into 3 adjacent hexagon cells.  The technology did not exist then and the frequencies had not yet been allocated. Cellular technology was undeveloped until the 1960s, when Richard H. Frenkiel and Joel S. Engel of Bell Labs developed the electronics.
In Europe, radio telephony was first used on the first-class passenger trains between Berlin and Hamburg since 1926. At the same time, radio telephony was introduced on passenger airplanes for air traffic security. Later radio telephony was introduced on a large scale in German tanks during the second world war After the war German police in the British zone of occupation first used disused tank telephony equipment to run the first radio patrol cars. In all of these cases the service was confined to specialists that were trained to use the equipment. In the early 1950s ships on the Rhine were among the first to use radio telephony with an untrained end customer as a user.
In 1967, each mobile phone had to stay within the cell area serviced by one base station throughout the phone call. This did not provide continuity of automatic telephone service to mobile phones moving through several cell areas. In 1970 Amos Edward Joel, another Bell Labs engineer, invented an automatic "call handoff" system to allow mobile phones to move through several cell areas during a single conversation without loss of conversation.
In December 1971, AT&T submitted a proposal for cellular service to the Federal Communications Commission (FCC). After years of hearings, the FCC approved the proposal in 1982 for Advanced Mobile Phone Service (AMPS) and allocated frequencies in the 824-894 MHz band. Analog AMPS was superseded by digital amps in 1990.
Recognizable mobile phones with direct dialling have existed at least since the 1950s In the 1954 movie Sabrina the businessman Linus Larrabee (played by Humphrey Bogart makes a call from the phone in the back of his limousine.
The first fully automatic mobile phone system, called MTA (Mobile Telephone system A), was developed by Ericsson and commercially released in Sweden in 1956. This was the first system that didn't require any kind of manual control, but had the disadvantage of a phone weight of 40 kg. MTB, an upgraded version with transistors (weighing "only" 9 kg), was introduced in 1965 and used dual-tone multifrequency signaling. It had 150 customers in the beginning and 600 when it shut down in 1983.
One of the first truly successful public commercial mobile phone networks was the ARP network in Finland, launched in 1971. Posthumously, ARP is sometimes viewed as a zeroth generation (0G) cellular network, being slightly above previous proprietary and limited coverage networks.
On April 3, 1973, Motorola employee Dr. Martin Cooper placed a call to rival Joel Engel, head of research at AT&T's while walking the streets of New York talking on the first Motorola DynaTAC prototype. Motorola has a long history of making automotive radio, especially two-way radios for taxicabs and police cruisers.