Mobile radio telephone is a wireless communication system that existed before modern cellular communication could happen. Called 0G or pre cellular, mobile radio telephone preceded 1G – the first generation of wireless communication technology. The pre cellular generation was based on half-duplex communication, which means people couldn’t talk simultaneously on the phone. When one person talked, the person at the receiving end had to wait for his turn to respond.

The mobile radio telephone system was commercially available and not restricted only to the government or special departments such as the police department, military, etc. Though considered mobile, mobile radio telephone devices weren’t truly mobile and usually came mounted in vehicles such as trucks or cars. There were briefcase models as well, which were not compatible with vehicles.

Background

The idea of a mobile radio telephone was brought to light in 1946 by Bell System (telephone service provider; ceased operations in 1984) and Motorola. Back then, the calls were pushed through manually and not automatically. In 1962, Bell System launched Improved Mobile Telephone Service (IMTS), which resulted in the calls becoming automatic.

Technology

Mobile radio phones were based on multiple technologies such as:

  • Advanced Mobile Telephone System (AMTS): A radio communication method that was predominantly used in Japan.
  • Mobile Telephone Service (MTS): A pre-cellular mobile telephone standard that links to Public Switched Telephone Network (PSTN).
  • Public Land Mobile Telephony (PLMT): A land mobile telephone system that was based in Norway.
  • Push to Talk (PTT): A cellular phone functionality that entails a button mechanism for switching a device from voice reception to voice transmission mode.
  • Improved Mobile Telephone Service (IMTS): As its name indicates, IMTS is an improved version of MTS that happened in 1964.  

Device Design and Functionality

The mobile device had a couple of primary parts: transceiver (transmitter – receiver) and a portion that had the dial keys and display, called head. The transceiver part stayed in the vehicle trunk, and it was connected to the head with a wire. The telephone stayed connected only if it was not more than 20 kilometers away from the local telephone network. The main antenna tower only had 25 channels, which meant not everyone could use the device. And naturally, there wasn’t any roaming facility available.