The cellular phone is the latest in a long line of mobile, portable, and wireless technologies extending back to the 1930s. Military forces were among the first to use mobile radio communications. Early mobile radio equipment for the military involved large transmitters aboard military vehicles with huge antennas and high transmitter power. The large, robust military vehicles were capable of accommodating the massive, power-hungry equipment.

The first use of radio communications for civilian land vehicles was primarily by police departments. The earliest systems were one-way, where the dispatcher could broadcast to all cars the location and nature of a problem. There was no return communication and thus no verification of a response to the problem, but it was better than nothing.

The first successful installation of a large two-way police radio system was for the Connecticut State Police in 1939. This system used a newly...